Despite continuing violence, a mounting toll of U.S. casualties and withdrawals of some coalition troops, Mr. Rumsfeld says that those he labels "thugs, assassins and former Saddam henchmen" will not be able to oppose peace and freedom in Iraq.

Mr. Rumsfeld tells reporters at the Pentagon, these enemies will not be allowed to win what he calls a "test of wills."

"The dead-enders, threatened by Iraq's progress to self-government, may believe they can drive the coalition out through terror and intimidation（胁迫）and foment（煽动）civil war among Sunnis and Shias or block the path to Iraqi self-rule but they are badly mistaken," he said.

The Pentagon has already responded to the latest challenge to coalition authority by ordering 20,000 U.S. troops who had been scheduled to return home to stay in Iraq an additional three months. That will keep the overall U.S. force level in the country at around 135,000.

Mr. Rumsfeld, responding to a reporter's question, says an increase in that number is not being actively considered.

But he says the Pentagon is prepared to add more troops if necessary. "Are we considering it, no. But have we prepared, you bet," he said.

The Defense Secretary's comments came the same day his Deputy, Paul Wolfowitz, appeared before the Senate Armed Services Committee and faced harsh（苛刻的）criticism.

Democrats on the panel complained that Mr. Wolfowitz, in his testimony, focused on the brutal nature of life under Saddam Hussein, not on the current situation in Iraq.

Senator Mark Dayton, a Minnesota Democrat, accused the Bush administration of trying to deceive members of Congress. "I find this extremely disappointing but I find it a continuation of this attitude that Congress is just to be duped（欺骗）and basically led along to this and the less that's presented to us that we can actually know what's going on the better and as long as we can be led to believe whatever suits the purposes of those who are carrying this out, then fine, just ignore us or lie to us or use us in whatever way you possibly can get away with and I find it just abhorrent（可恶的）," he said.

Mr. Wolfowitz rejected the suggestion the administration is deliberately misrepresenting the situation in Iraq.