(AP) The nation remains vulnerable to terrorists using false identification documents, say government investigators who say they were permitted to drive a truck into a Justice Department courtyard using false identification cards.

"Unless action is taken, individuals who want to cause harm can easily exploit these vulnerabilities," Robert Cramer, who directs special investigations for the General Accounting Office, told the Senate Finance Committee Tuesday.

GAO investigators visited driver's license agencies in Arizona, California, Maryland, Michigan, New York, South Carolina, Virginia and Washington, D.C. In each state, they obtained driver's licenses using forged documents, including counterfeit out-of-state licenses, which were made with inexpensive computer software, they reported.

Sen. Charles Grassley, R-Iowa, said the report lays out "a pretty scary scenario."

"If the GAO could do all these things, how can we be sure that your department can stop terrorists from doing it?" Grassley asked Asa Hutchinson, the undersecretary for border security at the Department of Homeland Security.

Hutchinson responded that 60,000 fraudulent documents have been confiscated at borders this year, and said training is being enhanced so agents will spot false documents. But he said the country has more than 240 different types of licenses, making it difficult for agents to determine what's legitimate. He said more uniform licenses and better technology are needed.

Youssef Hmimssa, who lived with members of a terrorist cell in Detroit and later helped the government convict several of them on terrorism charges, told the committee he easily obtained Social Security numbers, driver's licenses and even a U.S. passport after moving to Chicago in 1994 on a false French passport.

"If you have the right connection, you can get anything," said Hmimssa, who testified from behind a tightly guarded screen. The Moroccan immigrant is awaiting sentencing on charges of credit card and document fraud.

Hmimssa said the United States needs more advanced identification systems, such as identity cards with microchips in them or identification by eyes or fingerprints. Hmimssa said it was easy for him to obtain passports and Social Security cards on the black market and forge documents on his home computer. Even the special ink used on one government form was readily available, he said.

"There's a lot of people out there that will do more than I, that are more expert than I," Hmimssa said.

Richard Convertino, the assistant U.S. attorney who led the prosecution of the Detroit cell, said Hmimssa made fake documents for associates of the terrorist cell. He said they wanted the documents to set up drop locations for weapons or other materials, bring friends to the United States, practice shooting at target ranges and travel anonymously.

"The only limiting factor, seemingly, is one's imagination," Convertino said.

Sen. Jim Bunning, R-Ky., expressed exasperation at the Social Security Administration. He said he has been asking the agency to require microchips or fingerprints on Social Security cards for the last 10 years.

"We're going to have to pass a law to make it work," he said, after Hmimssa confirmed that having a Social Security number was key to obtaining other identification.

James Lockhart, deputy commissioner of Social Security, responded that his agency is now verifying any documents filed by immigrants with the Department of Homeland Security before providing a Social Security number.