Updated

President Bush signed a new law Thursday requiring stiff prison sentences for people convicted of using or providing fake IDs in committing terrorist acts and other types of crime.

The law is an important step in combating a type of crime that had 10 million U.S. victims last year, the president said in a signing ceremony at the White House.

He said identity theft "undermines the basic trust on which our economy depends," robbing its victims of nearly $50 billion in fraudulent transactions.

Identity thieves "can steal a victim's financial reputation" by running up bills that hurt the victim's credit rating, Bush said.

The legislation is meant to take away judges' ability to give probation, reduced sentences or concurrent sentences for identity theft linked to felony crimes. It was approved with bipartisan support, with lawmakers such as Sen. Dianne Feinstein (search), D-Calif., saying prosecutors need better tools to punish identity theft, especially when it is used to commit terrorist acts.

A provision imposing mandatory five-year prison terms would apply to people convicted of using or providing fake IDs to help terrorists. Providing fake IDs for non-terrorism-related crimes would carry a two-year prison term.

The legislation was sponsored by House Judiciary Committee Chairman James Sensenbrenner (search), R-Wis., who said Al Qaeda and other terrorist organizations increasingly turn to stolen identities to hide themselves from law enforcement.

In trips to three Midwest states this week, the president used national security to energize Republican audiences. At his last stop Wednesday night in Green Bay, Wis., he told a crowd of several thousand cheering supporters, "If America shows weakness or uncertainty in this decade, the world will drift toward tragedy."

"I will never relent in bringing justice to our enemies," Bush said as he linked terrorism and Saddam Hussein's regime in Iraq.

Bush invoked the memory of his visit to the site of the fallen World Trade Center towers on Sept. 14, 2001, "a day I'll never forget."

Workers stood in the ruins at Ground Zero and demanded action, chanting to the president, "Whatever it takes," he recalled.