Faced with the prospect of a U.S. debt deal that could substantially shrink the military budget, U.S. Defense Secretary Leon Panetta posted a letter to Pentagon employees warning against "misguided" cuts that could imperil the military's ability to perform.

The deal struck by Congress calls for an initial round of about $1 trillion in cuts, which White House officials estimate would slice $350 billion out of the Pentagon's budget over the next decade, followed by a second phase that requires Congress to generate an additional $1.5 trillion in deficit reduction. If Congress fails to reach an agreement on the $1.5 trillion, half of that amount will automatically be deducted from defense spending.

Panetta acknowledged in his letter the need to tame the ballooning national debt, which he said could endanger national security, and noted that the Pentagon is prepared to share the burden by tightening its spending. But he said he would fight against "hasty, ill-conceived" reductions that reflected political calculations, such as the possibility of Congress triggering the automatic cuts.

"If that happens, it could trigger a round of dangerous across-the-board defense cuts that would do real damage to our security, our troops and their families, and our ability to protect the nation," Panetta wrote. "This potential deep cut in defense spending is not meant as policy. Rather, it is designed to be unpalatable to spur responsible, balanced deficit reduction and avoid misguided cuts to our security."

In a subsequent briefing with reporters, a senior Pentagon official said that deep cuts could spur a round of layoffs, although he declined to provide specifics.

"I'd rather avoid scaring our employees," the official said, according to The New York Times.

Prior to the debt talks, President Barack Obama had already asked the defense department to locate $400 billion in savings over the next decade. The anonymous official said that the Pentagon would continue to target that number but would fight against cuts that exceeded it, saying the second phase of the debt deal should spare the military.

"I would expect them to focus on entitlements and taxes," he said.