Defense Department leaders ratcheted up their warnings to Congress about the threat of automatic budget cuts, with the U.S. military’s top uniformed officer even suggesting today that the cutbacks could lead to war.

“We can’t yet say precisely how bad the damage would be, but it is clear that sequestration would risk hollowing out our force and reducing its military options available to the nation,” said the chairman of the Joint Chiefs of Staff, Army Gen. Martin Dempsey, at a hearing of the Senate Appropriations Subcommittee on Defense. “We would go from being unquestionably powerful everywhere to being less visible globally and presenting less of an overmatch to our adversaries, and that would translate into a different deterrent calculus and potentially, therefore, increase the likelihood of conflict.”

Dempsey and Defense Secretary Leon Panetta have consistently warned about the harmful effect on the Pentagon of sequestration, which are automatic cuts of nearly a half-trillion dollars that would occur over the next nine years — on top of the roughly $490 billion over the next decade already in train. Both sets of cuts are required by last year’s debt ceiling law.

Panetta reiterated a warning to Congress that the defense authorizing and appropriations committees’ additions to the defense budget would have to be paid for by subtracting from other accounts, which in turn could result in a “hollowing out” of the military.

He took particular aim at lawmakers’ resistance to administration plans to retire aging aircraft and ships; proposed legislative caps on the drawdown of personnel levels in the Army and Marine Corps; and Congressional opposition to Pentagon plans to increase fees and deductibles for retirees participating in the Tricare health care network.

On another matter, Panetta disclosed that the Defense Department is about to seek another multibillion-dollar reprogramming of previously appropriated fiscal 2012 funds to pay for bulking up force levels in the Middle East, bankrolling an Israeli anti-rocket system called Iron Dome and paying higher-than-expected fuel bills.

He said that Pakistan’s refusal for more than half a year to allow NATO supply missions to use ground routes through its territory is forcing coalition forces to use other routes that are costing the Pentagon an additional $100 million a month. He said fuel costs are also $3 billion higher than expected.

Senate Armed Services ranking member John McCain (R-Ariz.) has assailed the ever-larger amount of Congressional appropriations that are being redirected to other purposes via such reprogramming requests, as well as the increasing use of such requests to start new programs.