Defense Secretary Donald H. Rumsfeld tried Thursday to sell the Senate Armed Services Committee on his decision last week to cancel the Crusader mobile cannon program.

The key behind the decision, he said, was the need to spend finite resources wisely by focusing on new technologies to face the enemies of the future.

"It is clear that continuing to fund a program we know will not best meet the mission would be irresponsible and a misuse of taxpayers' dollars," he said. "If there is one thing that Sept. 11 has taught us, it is that we can no longer ignore the warnings of the past or delay preparation for the future."

Terminating Crusader "is not about killing a bad system," he said. The issue, he said, "is about forgoing a system originally designed for a different strategic context to make room for more promising technologies that can accelerate transformation."

Committee Chairman Carl Levin, D-Mich., questioned Rumsfeld's abrupt change of view: "Until very recently the civilian and military leadership of the Defense Department consistently and strongly supported the Crusader program in testimony before the Congress."

Levin cited a Pentagon inspector general's finding that the Army first learned about Crusader's cancellation from a contractor. Word quickly spread to Capitol Hill, prompting a public announcement by Rumsfeld.

"We shouldn't let leaks drive policy, or else we're all going to be driven crazy and make bad decisions," Levin said.

Deputy Defense Secretary Paul Wolfowitz said the timing was driven not by leaks but by the "need to get information to the committee in a timely fashion for your deliberations" on the 2003 defense budget.

The Crusader has some strong supporters on Capitol Hill.

Despite a veto threat, the House last week voted for a defense authorization bill for the 2003 budget year that included the Bush administration's previously requested $475 million for Crusader, plus nonbinding language telling the Pentagon not to kill the program before producing a study on alternatives.

The Senate Armed Services Committee's version of the bill also contained the $475 million, but Levin said senators included no orders about the Crusader's future so they could hear first from Rumsfeld.

The Crusader is planned as a 40-ton, self-propelled cannon designed to rain 155 mm shells every six seconds on enemy forces more than 25 miles away. Slated as an $11 billion program, $2 billion has already been spent. The only one built so far weighs 60 tons, Rumsfeld said.

Rumsfeld and other critics have said it's too big and too unwieldy to fit in with the Army's plans for a lighter, faster and more mobile force. He said it would take 60 to 64 giant C-17 transport planes — one half the fleet — to move 18 Crusaders with all their accouterments to a foreign battlefield.

Supporters — who until last week included Rumsfeld, Wolfowitz and Army Secretary Thomas White — said Crusader would save soldiers' lives by hitting enemy forces before they are within striking range of U.S. troops.

Army Chief of Staff Gen. Eric Shinseki told the committee the Crusader remains the best answer to the military's artillery needs.

Committee reaction was mixed.

"I hope that you succeed here," Sen. John McCain, R-Ariz., told Rumsfeld. "All of us should be aware that if you fail here, it would be very difficult to make any of the much needed changes and transformations that you committed to at your confirmation hearings in response to questions from members of this committee."

But Sen. Max Cleland, D-Ga., told Rumsfeld, "I'm embarrassed for you and the department." Questioning how the money from Crusader would be used, Cleland said, "I'm not going to buy a pig in a poke, not with troops in the field out there needing artillery support."