The head of the House Armed Services Committee on Wednesday told the nation’s top military brass that their credibility “is on the line” if they don’t give greater details about how budget cuts will affect national security.

“Gentlemen, for two years you or your predecessors have come to this committee describing the consequences of sequestration in generalities and percentages,” California Republican Rep. Howard P. “Buck” McKeon told the military service chiefs in opening a hearing on Capitol Hill.

“Today I expect to hear — in very clear terms — what elements of that security you will no longer be in a position to provide” should the cuts continue, McKeon told the chiefs of staff of the Army, Navy, Air Force and Marine Corps. He was referring to the automatic spending cuts that kicked in March 1; they are projected to slash $52 billion from the defense budget for fiscal 2014, resulting from Congress’ failure to trim the federal deficit.

Army Chief of Staff Gen. Ray Odierno was ready with some figures.

He testified the Army would have to shrink its active duty force by 26 percent, to 420,000 people. Odierno also said that readiness would be degraded to the point where 85 percent of the force by the end of the next budget year would not be prepared to deploy if a conflict popped up somewhere in the world.

Air Force Chief of Staff Gen. Mark Welsh III said his service in the next budget year would have to cut flying hours by 15 percent, personnel by 25,000, or 4 percent, and aircraft by 550, or 9 percent.

Top civilian and uniformed defense officials tried for months to stop the cuts and have warned repeatedly of severe and unacceptable effects on the U.S. military if Congress doesn’t end them.

Rep. Adam Smith of Washington, the ranking Democrat on the committee, said lawmakers were to blame.

“You all have extremely hard jobs, and I am afraid that we in Congress have not made them any easier by allowing sequestration to take effect,” Smith told the chiefs in a statement prepared for the hearing.

“Without a doubt, the Department of Defense must become more efficient,” Smith said. “But sequestration will continue to force the department to make unacceptable cuts.”