When the men came together in Nairobi, Kenya, they formed one of Osama bin Laden's deadly terror cells, carrying out the twin U.S. embassy bombings in East Africa three years ago, according to federal court testimony. Two of the men had direct connections to bin Laden. Others involved in the attacks appeared to have been contracted out from other groups.

In an extraordinary speech before Congress Thursday, President Bush launched a relentless U.S. campaign against bin Laden's al-Qaida network and all it touches.

''Our war on terror begins with al-Qaida, but it does not end there. It will not end until every terrorist group of global reach has been found, stopped and defeated,'' the president said.

Testimony from the trials into the embassy bombings and the 1993 World Trade Center bombing - both masterminded by bin Laden - has given counterterrorism experts new insight into the operations of the Saudi dissident and may help the United States strike at his global network of terrorist cells.

At least two different cells that had been operating in Hamburg, Germany, and Delray Beach, Fla., were involved in last week's terror attacks on the United States. Others left fingerprints in Boston, Jersey City, N.J. and Daytona Beach, Fla.

On Thursday, German officials said their country may be home to as many as 100 terrorists who were trained in Afghan camps run by bin Laden.

Intelligence experts say hundreds of cells working for bin Laden's Afghanistan-based al-Qaida network or other terrorist groups are operating in dozens of countries - raising money, establishing businesses and safe houses, studying and receiving military training. Some are aided by governments such as Iraq and Iran while still others are independent operatives offering specialized services to the cells.

''Al-Qaida is really a fraternity of fundamentalist Islamic terrorist networks around the world,'' said Michael M. Swetnam, who co-authored a book this year on bin Laden's operations. ''These groups communicate regularly, train each other's fighters, share resources, funding, financing and people.''

From as early as 1983 and until the late 1990s, Iran was training suicide pilots at a camp in the northeast town of Wakilabad, according to Rep. Eric Cantor, R-Va., who chairs a congressional task force on terrorism and unconventional warfare.

Swetnam says Iraq - a traditional enemy of Iran - has provided financial and technical support to bin Laden's fighters while groups that enjoy Iranian sponsorship, such as Hezbollah, are also affiliated with al-Qaida.

Bush made it clear Thursday that the United States would go after any organization that supported or harbored the terrorists that carried out the Sept. 11 attacks on the World Trade Center and the Pentagon.

''Our enemy is a radical network of terrorists and every government that supports them,'' Bush said.

A congressional report released Sept. 10 - one day before the attacks - details more than 30 countries, including the United States, where bin Laden has cells operating.

Bush talked of ''thousands of these terrorists in more than 60 countries.''

The report, written by Kenneth Katzman, a specialist in Middle East affairs, also lists 19 terror organizations, several with ties to bin Laden, and rates their activity levels. Bin Laden's Afghanistan-based al-Qaida has the highest rating of activity, while the Palestinian Islamic Jihad and Hamas are listed as the next most active groups.

In his speech, Bush linked al-Qaida to other organizations, including the Egyptian Islamic Jihad and the Islamic Movement of Uzbekistan - both identified as terror groups in the congressional report.

Bush demanded that Afghanistan's leadership, the hardline Taliban militia, ''deliver to United States authorities all of the leaders of al-Qaida who hide in your land.''

Afghanistan has become a haven for thousands of activists believed to be preparing to overthrow more moderate Muslim regimes in Algeria, Egypt, Jordan, Saudi Arabia, Yemen and the Islamic states of nearby Central Asia that were part of the former Soviet Union.

Last year, Jordanian intelligence experts cracked a sizable cell that had been planning a spectacular attack on American and Israeli tourists during millennium celebrations. Jordanian officials say one defendant has admitted he received bomb-making training in Afghan guerrilla camps run by bin Laden.

Frank Cilluffo, a counterterrorism expert with the Washington-based Center for Strategic and International Studies, said: ''Afghanistan has become the place for a pretty lethal mix of ugly folks running around and at some point we will want to drain that swamp.''

Once the other militants leave Afghanistan and return to their own organizations, Swetnam said they could apply for ''grants'' from al-Qaida to carry out their own operations.

''A group like Hamas says they want to blow up a department store in Israel and offers up a proposal with a cost estimate. If it's approved they could receive whatever is needed to support the plan including money and training'' Swetnam said.

Yonah Alexander, a professor at George Washington University and a counterterrorism expert, warned that the operatives must be found soon.

''Dozens of operations are waiting to be hatched and carried out by people who are integrating into societies while they wait for their missions,'' he said.