Several said that Mr. White had violated terms of an ethics agreement he signed before becoming the Army secretary.

The decision sets the stage for a showdown with the weapon's influential supporters in Congress and the embattled Army secretary who fought to save it.

"Public safety remains our principal interest," Les Brownlee, the acting Army secretary, said in a statement.

"Everyone in the world wants to help us fix the Army, except give us an Army secretary," the senior defense official said.

Mr. White, who will continue as Army secretary, also favors creating a combat command for homeland security under the direction of a four-star officer.

Ms. Greenhouse, known as Bunny, sent her letter to the acting Army secretary, with copies to Congress and the news media.

The job of Army secretary is outside the military chain of command, but the position exercises responsibility over areas like personnel, weapons development and financial management.

Mr. White was an Enron executive for 11 years before becoming Army secretary last May.

Mr. Harvey, the Army secretary, ordered an investigation last September to help address families' concerns.

But the rules allow for the Army secretary or top Veteran Affairs Officials to allow exceptions.