In 2000, David Coleman Headley called a phone number he saw on a recruiting poster in a mosque in Pakistan, and in doing so launched a nearly decade-long career as a terrorist.

For the soft-spoken Pakistani-American who admits he helped carry out the deadly 2008 terror rampage in Mumbai, it was simple: "I went to a meeting."

Born in Washington, D.C., Headley — who is now the government's star witness in the trial of a businessman accused in the Mumbai attacks — has an American mother and Pakistani father, fair skin and speaks many languages including perfect English. He has a U.S. passport, attended six militant training courses in Pakistan and became adapt at blending in wherever he traveled.

When it comes to terrorists, Headley is a rare breed.

But in the years since Headley's unusual mix of dual citizenship and ability to travel internationally made him an ideal terrorist foot soldier, it's become much easier for militants to compensate for there not being enough people like Headley to recruit.

These days extremists from anywhere in the world can prey on disaffected men and women as they surf the web in the privacy of their own basements. English-speaking Islamic clerics proselytize on YouTube about perceived Western-imposed injustices. They publish flashy Internet magazines written in English with articles about how to build a bomb in your mother's kitchen and advice on how not to get caught.

If someone wants to join a foreign jihadist cause, there are plenty of options to choose from, and the extensive travel and training like Headley had — while still valuable to terror groups — is no longer the key to success.

"There are terrorists, and then there are terrorists," said Juan Zarate, a senior counterterrorism official in the Bush administration. After spending the past decade disrupting known terrorist networks and their hideouts, the United States is now seeing fewer seasoned and honed terrorists likely Headley and more fly-by-the-night Internet radicals, Zarate said.

Take Nidal Hasan, the U.S. Army major who is accused of shooting to death 13 people at Fort Hood, Texas, in 2009. Hasan communicated about the merits of jihad with a radical Islamic cleric who is hiding with al-Qaida's offshoot in Yemen but didn't spend years at a terror training camp.

Then there's Faisal Shahzad, the man accused of trying to blow up a truck last year on a busy New York City street corner. The Pakistan Taliban provided Shahzad with about $15,000 and only five days of explosives training in late 2009 and early 2010, just months after he became a U.S. citizen.

There are also individual agents, like 21-year-old Arid Uka, who radicalized on his own, by looking at terrorist websites before storming a U.S. military bus at a German airport in March, killing two U.S. airmen.

"Those that actually have training overseas, those that actually have connections to sophisticated terrorist organizations are going to be more lethal," said Frank Cilluffo, director of George Washington University's Homeland Security Policy Institute.

But, he said, terrorists and recruitment methods come in various shapes, sizes and forms. While terror organizations are still able to blossom in areas with little or no effective government, the Internet has become yet another ungoverned space — and it's easier to get to.

"We can't ignore or discount those that are literally turning to the Internet and being radicalized and recruited," Cilluffo said. "They can cause harm."

Headley pleaded guilty in 2010 to laying the ground work for the Mumbai attacks that killed more than 160 people and is now testifying in a federal terrorism trial against his longtime friend, Chicago businessman Tahawwur Rana, who is accused of giving Headley cover when he made multiple surveillance trips to Mumbai to scout sites. Rana has pleaded not guilty.

During his testimony, Headley detailed his numerous trips to India and Pakistan and his face-to-face and email conversations with both his handler from Lashkar-e-Taiba, the militant group that claimed responsibility for the Mumbai siege, and a Pakistani intelligence officer known only as "Major Iqbal." Headley claims both helped with the plot. On Thursday, Headley described how he started working with another Pakistani militant to plan another attack, this time on a Danish newspaper that in 2005 printed cartoons of the Prophet Muhammad. That attack never occurred.

For more than a decade, Headley managed to stay off the radar as he flew from one continent to another to meet with terror operatives. To blend in wherever he traveled, Headley carried a cross, had red bracelets commonly worn by Hindus, and kept the book, "''How to Pray Like a Jew" in his bag. He even changed his name in 2006 from Daood Gilani to something less likely to raise eyebrows — David Coleman Headley.

His travels eventually caught up with him. In the summer of 2009, U.S. officials were looking for someone named "David" who was a frequent international traveler.

In August 2009, customs officials found Headley and the FBI was soon listening to his conversations with associates and reading his emails. On Sept. 7, 2009, agents listened to Headley tell Rana about "four targets that I liked." Rana told Headley even if he hit those four targets, Headley would still want more.

On May 25, a prosecutor asked Headley: "Is that true?"

Speaking matter-of-factly about his decade in global terror, Headley responded, "Probably."