U.S. officials in Pakistan have now visited the men in custody, after their disappearance late last month prompted a frantic search by friends and family and an investigation by worried counterterrorism officials.
"We have had access to the five detainees," Secretary of State Hillary Rodham Clinton told reporters Thursday at an unrelated news conference. She called the move "part of the usual outreach" of the U.S. government and declined further comment.
Javed Islam, a regional police chief in Pakistan, said the men wanted to join militants in the country's tribal area before crossing into Afghanistan and said they met with a banned military organization, Jaish-e-Mohammed in Hyderabad, and with representatives of a related group, Jamat-ud-Dawa, in Lahore.
Another law enforcement official, Usman Anwar, the local police chief in Sargodha, told The Associated Press that the five are "directly connected" to the al Qaeda terrorist network.
"They are proudly saying they are here for jihad" or holy war, Anwar said.
A Pakistani government official in Sargodha, who asked not to be identified, told CBS News' Sami Yousafzai that information obtained as a result of the Americans' arrest led to a subsequent raid in the city, during which key Jaish-e-Mohammed figure Qari Saeed was arrested.
The men used the social networking site Facebook and the Internet video site YouTube to try to connect with extremist groups in Pakistan, said S.M. Imran Gardezi, the press minister at the Pakistani Embassy in Washington. When they arrived in Pakistan, they took that effort to the street.
"They were trying to link up to some groups, but there is no evidence for now that there was a definite plan," Gardezi said.
Local Pakistanis became suspicious of the young men and tipped off police, he said. Police arrested the group in a home belonging to the uncle of one of the men. Gardezi said the uncle had past ties to extremist groups.
Gardezi said the men have not been turned over to the FBI and said Pakistan intended to carry out its own legal process.
Another break in the case came not from federal agents or spies, but parents worried their sons may have made a terrible decision.
The families, based in the northern Virginia and Washington, D.C., area, were particularly concerned after watching what is described as a disturbing farewell video from the young men, showing scenes of war and casualties and saying Muslims must be defended.
"One person appeared in that video and they made references to the ongoing conflict in the world and that young Muslims have to do something," said Nihad Awad, of the Council on American-Islamic Relations, or CAIR. The video has not been made public.
After the disappearance of the five men in late November, their families, members of the local Muslim community, sought help from CAIR, which put them in touch with the FBI and got them a lawyer.
The men range in age from 19 to 25. One, Ramy Zamzam, is a dental student at Howard University. Pakistani police officer Tahir Gujjar identified the others under arrest as Eman Yasir, Waqar Hasan, Umer Farooq and Khalid Farooq.
They were arrested Wednesday at a house in Sargodha linked to Jaish-e-Mohammed, Pakistani officers said. Islam said investigators are sharing their findings with FBI officials now in Sargodha.
On the heels of charges against a, the case is another worrisome sign that Americans can be recruited within the United States to enlist in terrorist networks.
President Barack Obama declined to talk specifically about the case Thursday, but said, "We have to constantly be mindful that some of these twisted ideologies are available over the Internet."
Obama, in Oslo, Norway, to accept the Nobel Peace Prize, also praised "the extraordinary contributions of the Muslim-American community, and how they have been woven into the fabric of our nation in a seamless fashion."
A Virginia Muslim leader said the five men did not seem to have become militant before they left the U.S.
"From all of our interviews, there was no sign they were outwardly radicalized," said Imam Johari Abdul-Malik.
Pakistan has many militant groups based in its territory and the U.S. has been pressing the government to crack down on extremism. Al Qaeda and Taliban militants are believed to be hiding in lawless tribal areas near the Afghan border.
In Washington, a spokeswoman for the FBI's local office said agents have been trying to help find the men.
"We are working with Pakistan authorities to determine their identities and the nature of their business there if indeed these are the students who had gone missing," said the spokeswoman, Katherine Schweit.
According to officials at CAIR, the five left the country at the end of November without telling their families.
After the young men left, at least one phoned his family still claiming to be in the United States, but the caller ID information suggested they were overseas.
A Howard University spokesman confirmed Zamzam was a student there but declined further comment.
Samirah Ali, president of Howard University's Muslim Student Association, said the FBI contacted her last week about Zamzam, and told her he had been missing for a week. Ali said she's known Zamzam for three years and never suspected he would be involved in radical activities.
"He's a very nice guy, very cordial, very friendly," Ali said.
One of Zamzam's younger brothers, interviewed at the family's Alexandria, Va., apartment, said Zamzam has a 4.0 grade-point average.
"He's a good guy," the brother said, identifying himself only by a nickname, "Zam." "He's a normal Joe."