hen helicopters touched down in the mountains in early March at the start of the deadliest battle for Americans in Afghanistan, the infantrymen who rushed out immediately came under surprisingly intense fire. Bursts from rifles and machine guns were joined by explosions from well-placed mortar rounds, a coordinated mix of firepower that is one mark of a capable military force.

Specialist Wayne Stanton, a 10th Mountain Division soldier who was wounded in the skirmish, later paid his foes a soldier's grudging compliment. "They knew what they were doing," he said.

The Taliban and Al Qaeda resistance near Gardez was a bracing display for fighters who, despite their appearance as a ragged band of fanatics, had achieved a level of competence that American military officials say was on par with the world's best guerrilla forces. It also demonstrated the degree to which Osama bin Laden and other jihad leaders had turned Afghanistan's network of training bases and guest houses, typically described as terror schools, into a sort of two- tiered university for waging Islamic war.

Details of the training emerge in hundreds of documents and thousands of pages collected from those schools by reporters from The New York Times, and from interviews with American government and military officials.

The documents — including student notebooks, instructor lesson plans, course curriculums, training manuals, reference books and memorandums — show that one tier, by far the busiest, prepared most of the men who enlisted in the jihad to be irregular ground combatants, like those who repulsed the 10th Mountain Division's helicopter-borne assault. The other provided a small fraction of the volunteers with advanced regimens that prepared them for terrorist assignments abroad.

American military instructors who reviewed the documents said the first tier of instruction was sophisticated in a conventional military sense, teaching, one said, "a deep skill set over a narrow range" that would reliably produce "a competent grunt." The second tier was similarly well organized, albeit with more sinister curriculum.

Implicit in the split levels of training was the Islamic groups' understanding of the need for different sets of skills to fight on several, simultaneous fronts: along trench lines against the Northern Alliance in Afghanistan; against armor or helicopter assaults from conventional foes in Chechnya; as bands of foot-mobile insurgents in Kashmir, Central Asia or the Philippines; and as classic terrorists quietly embedded in cities in the Middle East, Africa, the former Soviet Union and the West.

To instill these diverse lessons, the schools applied ancient forms of instruction — teachers pushing students to copy and memorize detailed tables and concepts — to modern methods of killing. Michael R. Hickok, a professor at the Air War College in Montgomery, Ala., said they used "Islamic pedagogy to teach Western military tactics."

Evident as well in the documents, which were translated for The Times, were signs that in developing martial curriculums, the groups were cannily resourceful in amassing knowledge. Some lessons were drawn from manuals from the former Soviet Union. Others, the use of Stinger missiles or Claymore mines, were derived from instruction underwritten by the Pentagon and the Central Intelligence Agency in the 1980's, when Washington backed the Afghan resistance against Soviet occupation.

In the years after the Soviets withdrew and American money evaporated, the groups aggressively cribbed publicly available information from the United States military and the paramilitary press. Ultimately, American tactics and training became integral parts of the schools.

One camp, used by the Islamic Movement of Uzbekistan, gave instruction in movements by four-man fire teams that was modeled after formations used by the United States Marine Corps, according to military instructors who reviewed it. The Uzbeks also used reconnaissance techniques long taught at the Army's Ranger School in Fort Benning, Ga. Other documents show that jihadi explosives training covered devices and formulas lifted from a Special Forces manual published in 1969.

While these materials are available through open sources, from on-line booksellers to rural gun shows, military officials said it was a feat to digest far-flung sources, translate them into Arab and Asian languages and assemble them in an orderly way. Bomb-making instruction, for instance, combined the electrical engineering necessary to make detonation systems with Vietnam-era Army formulas for home- brewed explosives, then was translated into Arabic, Uzbek and Tajik. "It indicates a tremendous amount of filtering and organization to get to that," an American military instructor said.

Moreover, notebooks from several camps demonstrate that even in courses taught in different languages and hundreds of miles apart, many lessons were identical, sharing prose passages, diagrams and charts. This was an important achievement, military officials said, as it created compatibility between members of what essentially became an Islamic foreign legion.

It also marked a significant advance beyond training that the United States sponsored for Afghans in the 1980's.

"One of the problems we had against the Soviets was getting the mujahedeen to be uniform," said an American official familiar with that movement. "We couldn't get them on the same page. When you went to one valley, they fought one way. When you went to the next, they fought another. To the extent these guys were able to level the training and make it consistent, they were on the right track."

Core Curriculum

Afghanistan's dozen or so jihad schools were hard, spartan places, compounds with dusty classrooms in arid mountains or on the sun-baked steppe where men hunched over note pads and applied an ageless form of learning to guerrilla war. Outside were obstacle courses and mazes of barbed wire and trenches for infantry drills. Inside, men slept on mats in buildings made of mud.

Jihad groups had the means to reproduce lesson plans in bulk, and distribute them in neat folders, as most modern militaries do. But they chose not to, opting instead to have students copy material by longhand, meticulously following instructors who stood before the class. Dr. Charles P. Neimeyer, a dean at the Naval War College in Newport, R.I., said camps treated each student "like a monk in a monastery in the Middle Ages."

From these carefully scribed records, dropped or discarded last fall by recruits and the veterans who trained them, a pattern emerges.

The core curriculum began simply. It opened with classes in Kalashnikov rifles, the hardy series of automatic weapons designed in the Soviet Union after World War II and since then exported worldwide. The weapons were the predominant arms in Taliban and Qaeda formations, and the jihadis, like American recruits learning to master M-16's, studied their history, design and operation. Then they turned to PK machine guns, 82-millimeter mortars and the RPG-7, a shoulder-fired rocket effective against armored vehicles and trucks.

Each class began with a modicum of history then plunged into important facts: names of components, steps to dismantle and clean them, characteristics of different munitions, steps to clear misfires and jams.

Together, the classes served as infantry weaponry 201, a course mastered by rote.

Students copied sections on how to fine- tune a rifle sight at short range to ensure accuracy at longer distances, a procedure known as zeroing. They recorded sections on directing rockets or controlled bursts of bullets and tracers at moving targets, on the ground or in the air. They reviewed several different shooting scenarios, scribbling down technical solutions for each.

The training, Professor Hickok said, was "a lot more sophisticated than a bare-bones, simple, `Here is your weapon, go forth.' "

American tactics instructors who reviewed the notebooks were similarly impressed. "They have standardized targets throughout their program of instruction," one said. "That's good stuff. That's professional. It shows you have standards, you have some level of shooting that's acceptable and not."

Most students also trained on the tripod- mounted heavy machine guns and antiaircraft pieces, which Afghan soldiers use to spray flak at planes but also to control roads, valleys and mountain passes. Some received classes covering the Dragunov, a sniper rifle with a telescopic sight.

Others studied portable antiaircraft missiles, including the American Stinger, the British Blowpipe and the Russian Grail. American officials have said concerns about these weapons in certain regions of Afghanistan kept coalition airplanes at high elevations, — out of the missiles' range, during sorties. (One American military official said a Stinger or Blowpipe was fired at a pair of United States Navy aircraft last fall. The pilots took evasive actions. The missile passed narrowly between them.)

Veterans also led their charges through demolition instruction covering mines and grenades, as well as TNT and plastic explosives. This training — seen in notebooks from Mazar-i-Sharif and Al Farouk, where the Talib from California, John Walker Lindh, trained — was geared for combat rather than terrorism, said American instructors who reviewed it. It surveyed the equipment and skills needed to mine roads, create obstacles or destroy infrastructure on the battlefield.

"It's not like, `How can you sneak an explosive onto a plane?' " a senior instructor with extensive demolition experience said. "It shows how you could blow up a bridge before it's crossed by the infidel regiment."

Similarly, lessons on booby traps — rigging explosives for surprise detonation, as when a pedestrian steps on a pad and closes an electric circuit, or crosses a trip wire and releases a time fuse's pin — resembled classes for American marines and soldiers, who are taught to create makeshift weapons for ambushes and defensive positions.

"That's the poor man's B-52, the booby traps," the instructor said. "They're effective; they're cheap and fairly easy to rig. The instructions in these notebooks would work."

But other subjects, which appear menacing in student notes — briefcase bombs, truck bombs or bombs that would detonate when a spring is depressed in a couch or bed — lacked enough detail to be effective, the instructors said. Their inclusion most likely served a clever purpose: giving students a sense of esprit with terrorists who had struck American embassies in Africa and military barracks in the Middle East.

"Most of that stuff with demolitions is motivational," the senior instructor said. "They've had huge successes with truck bombs against us, so they are going to use the truck bomb in the curriculum to reinforce the success, even if they do not realistically expect each of these guys to use a truck bomb. It reinforces their way of doing business. It reinforces their heritage."

Diverse Recruits

As the jihad camps grew during the 1990's, recruits arrived from at least 15 nations and speaking more than a half- dozen languages, conditions that posed a challenge for a force hoping to be cohesive. The documents show that the Islamic groups developed a uniform training program that assimilated recruits with different cultures and skills.

Reviews of notebooks from in or near Kunduz, Kabul, Rishkhor, Mazar-i-Sharif and Kandahar turn up the same hand-drawn diagrams for classes in weaponry, map reading, celestial navigation, trench digging, mortar employment and demolition.

The similarities bridge social differences and speak of the jihad's effective network. "The classes have the same prearranged instructor scripts, because you see the exact same classes being given in different years, different regions, different languages," said an American tactics instructor.

Another added: "This is why you can take so many different ethnic groups — foreigners, Afghans, people from either side of the Hindu Kush — and you can put them together, and they can fight together. They all have the same basic skills."

Moreover, the lessons were what curriculum experts call "modular," meaning self- contained. A student need not complete Lesson A to be ready for Lesson B. "That's a pretty sophisticated way to do this curriculum," said Professor Hickok, who reviewed several notebooks. "It makes the curriculum pretty adaptable."

It also allowed instructors to mix and match lessons for each jihad group's particular needs.

Recruits of the Pakistani group Harkat- ul-Mujahedeen received instruction in M- 16's, American-made rifles they could encounter while fighting in Kashmir, the disputed territory divided between Pakistan and India. Students trained to fight in Central Asia or Afghanistan, where M-16's are all but nonexistent, skipped these weapons.

In the end, the camps avoided almost entirely the painstaking rituals of state-run militaries: the weeks spent on proper wearing of uniforms, or marching, or procedures of garrison life and administration. They remained focused on jihad indoctrination and fighting skill.

"They are leaving the bureaucracy out, and teaching them a couple of basic things very, very well," one instructor said. "It is a classic saying: Master the basics; become brilliant at the basics. If you take care of those, when the time comes for combat, you'll do better than okay."

American officials estimate that 20,000 men received this training since Mr. bin Laden moved from Sudan to Afghanistan in 1996. Today they are scattered. Many died in airstrikes. Others were taken prisoner. Some were executed by the Northern Alliance. How many remain, and how organized they are, is unknown.

Advanced Courses

Although standard jihad training prepared recruits for ground combat, the line between guerrilla and terrorist could often grow fuzzy. Basic courses provided a martial foundation, and government officials said that with initiative and further study, the graduates could develop specialized terrorist skills, much as Timothy McVeigh, once a conventional American infantryman, later built the truck bomb that killed 168 people in Oklahoma City.

Al Qaeda and other groups did not leave this evolution entirely to chance. They were trying to do more than use guerrilla insurgents to topple Muslim governments they saw as secular or corrupt. They had declared war against infidels and were eager to carry the battle to where the infidels lived.

To further this end, students with special abilities were identified in basic camps and sent to courses that prepared them for more difficult missions. "We look at it as sort of being a winnowing process," an American official said. "There is sort of a scouting process going on."

Only a very small fraction of the jihadis are thought to have received the higher level of training, government officials say, but it was enough to improve the guerrilla forces and to turn loose a resourceful breed of killer on the larger world.

"Afghanistan," said Michael A. Sheehan, the State Department's counterterrorism coordinator during the last years of the Clinton administration, "was the swamp these mosquitoes kept coming out of."

There were two tracks: one for advanced infantry techniques, another for terror.

Infantry classes refined battlefield skills. One course, detailed in a notebook from Kunduz, was intermediate-level instruction in 82-millimeter mortars. Another, described in a syllabus found in Kabul, taught advanced land navigation. A third described using global positioning satellites and a scientific calculator to plot artillery firing data.

Records showed that as guerrillas advanced, their roles sometimes blurred. A series of courses, taught by Harkat and repeatedly described as a curriculum for "commandos," included instruction in sniping, interrogation, first aid, escape, evasion and hand-to-hand combat — all infantry tasks. But as the course progressed, its objectives grew darker, including "how to kill a policeman" and "traps, murder and terrorist moves."

Other courses also had military or terrorist applications, including one in espionage and another in secure communications, which has been effectively used by terrorist cells abroad.

Some lessons were wholly dedicated to terror.

Bomb-making instruction included recipes for brewing explosives and crude poisons from readily obtainable substances, including making an explosive booster beginning with a paste of ground aspirin and water.

The class further covered the manufacture, handling and storage of nitroglycerin, HMDT, C-4 and C-3. One document began with an explanation of the instructor's goals.

"God Almighty has ordered us to terrorize his enemies," it reads. "In compliance with God's order and his Prophet's order, in an attempt to get out of the humiliation in which we have found ourselves, we shall propose to those who are keen on justice, fighting against those who oppose them and those who diminish them until they receive fresh orders from God. To those alone, we present: `Rudimentary Methods in the Manufacturing of Explosive Materials Effective for Demolition Purposes.' "

Instructors included enough electrical engineering — uses of diodes, resistors, switches and more — to help students plan the wiring, power sourcing and fuses required to spark an explosive charge. Notebooks also included tips for putting familiar objects to nefarious use, like converting a hand set for a radio-controlled toy boat into a remote detonator. Government officials said those methods would work, in the right person's hands.

"This isn't for everybody," a senior American military instructor said. "This is for somebody who is smart."

Dr. Kamal Beyoghlow, a professor at the Marine Corps Command and Staff College in Quantico, Va., and a former counterterrorism officer at the State Department, said the curriculum reflected care and deliberation.

"The lesson is very well organized, extremely organized," he said. "It is the work of a methodical hand."

The jihad groups clearly were proud of it, and eager to pass its lessons around. One notebook ended with an Arabic passage: "We ask you, dear brother, to spread around this document on all the mujahedeen. Do not keep what you know a secret, if you please."

Graduates from courses like those — resourceful, smart men who have used simple materials to produce bombs that destroyed two American embassies and crippled a Navy warship — are the jihadis the government most fears, particularly if they were to expand their capabilities to include nuclear, chemical or biological weapons.

The American-led coalition says it has turned up no evidence that the men had reached this point, although they were actively educating themselves in the subject. But current and former officials warned that even if they lacked the technology or skill to make such weapons themselves, they still might deliver a terrifying blast. "What worries me," Mr. Sheehan said, "is their ability to get their hands on a weapon someone else has put together."

Experts also said they feared that bomb- making skills taught in advanced classes would be sufficient for making a "dirty bomb," in which spent radioactive material could be lashed to high explosives for a mildly radioactive blast.

Officials said papers from Kabul explaining uses of radioactive isotopes in agriculture and medicine, found in the same rooms as the explosive notebooks, indicate research into precisely that sort of weapon.

Military Models

All successful military organizations study one another, sizing up threats, identifying weaknesses, copying weapons and tactics. The jihad groups were no exception.

Law enforcement officials have described a multivolume set of terrorist instructions, dubbed the Encyclopedia of the Afghan Jihad, as a sort of master guide for the camps. Parts of the encyclopedia were found by The Times at four training sites, and officials said parts of its explosives section were incorporated into classes at the camps.

But records from students and teachers also show that most jihad courses lasted several weeks to a few months and that rather than covering the encyclopedia's breadth, stayed intensely focused on small sets of skills. To create those classes, the groups relied heavily on an array of sources obtained from the West: military training manuals, American hunting magazines, anarchist manuals, popular action movies, chemistry and engineering textbooks, and Web sites hawking James Bond-like tricks.

Signs of this collection effort are sprinkled throughout their documents. American military trainers who reviewed the jihadi students' notes quickly identified lessons from their own playbooks, including Islamic Movement of Uzbekistan reconnaissance techniques also used by Army Rangers, or four-man weapon deployments and formations — wedges, columns, echelons, lines — that are the Marine Corps standard.

One senior military instructor noticed a familiar streak of professionalism in class schedules, a carefully selected mix of lectures, demonstrations and practice. "Wherever they got this, it was modeled after somebody's program," he said. "It was not made by some guys on some goat farm outside of Kabul."

He was right. It had been cribbed from an appendix in a Marine Corps manual seeking to standardize sniper training, a copy of which was found with terrorist course schedules in a Harkat house in Kabul.

American influence also appears in jihadi explosives courses. For instance, chapters from the "Improvised Munitions Handbook," a United States Army manual published in 1969, were found by a Times reporter in the same Kabul guest house. Ink tracing on its pages show that it had been translated into Arabic. The manual, according to its introduction, was intended "to increase the potential of Special Forces and guerrilla troops by describing in detail the manufacture of munitions from seemingly innocuous locally available material."

It seems to be fulfilling its mission. The manual's diagram for using a laundry pin as part of a trip-release firing circuit was used in the basic demolition instruction at the Farouk camp. Other lessons, including how to make an antipersonnel bomb from a light bulb, were found in an advanced demolition notebook. (The light bulb device is similar to a weapon shown in a scene in the Burt Reynolds movie "The Longest Yard." The jihadis translated the manual to learn an additional step, as well as a way to use bulbs as detonators in larger bombs.)

This sort of resourcefulness is reminiscent of another Afghan war, current and former officials said. In the 1970's the Soviet Union trained a cadre of Afghan Army officers in its military academies, teaching them leadership and tactics. When the Soviet Army came in, many switched sides.

"These officers knew the Soviet Union's armor doctrine, and when the Russians tried to go up the valleys, some of them were right there, directing ambushes," said Dr. Joshua Spero, a professor at Merrimack College in Massachusetts and former Central Asia military planner for the Joint Chiefs of Staff.

But officials also noted that the breadth of the camps' curriculum search resulted in uneven quality. Some material was well- chosen, some not. Harkat had obtained a copy of "The Poisoner's Handbook," a book commonly sold by survivalist stores in the United States. Its information is insufficient for making mass-casualty weapons. "It's nonsense," one official said.

(The effort resembled some attempts to gather nuclear materials. Officials said, for instance, that Al Qaeda members have been duped by swindlers and sold bogus goods.)

Officials also said even useful references could be problematic. One said that while cautious handlers could use some Special Forces bomb recipes, others would endanger themselves. "People have had to be scraped off of their ceilings after trying these things," he said.

The jihadis seemed to know this. One notebook warned: "Make sure that first aid kits are available at all times in order to deal with any mishaps that might result from the performance of this experiment."

Whatever the shortfalls, the two tiers of training worked.

The small number of graduates of the top tier have struck American targets in Africa, the Middle East, Washington and New York. In 1999 customs officers caught another alumnus, Ahmed Ressam, with a functional bomb and plans to explode it at Los Angeles International Airport.

The battle near Gardez demonstrated that when American soldiers come down from the sky and fight within machine-gun range, the guerrillas have the training to turn them back. Two days after Specialist Stanton's unit withdrew, American soldiers again came under fire from machine guns and rocket-propelled grenades, this time as they tried to recover the body of Petty Officer Neil Roberts, a Navy Seal.

By the end of that day, seven Americans were dead.