Defense Secretary Leon Panetta, left, and Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff. (Mark Wilson — Getty Images)

Defense Secretary Leon Panetta on Monday described the failure of the supercommittee to come up with a deficit-reduction plan as a grave setback. He said he had never been more concerned about the ability of Congress to “forge common-sense solutions to the nation’s pressing problems.” He also joined President Obama in urging lawmakers to avoid any attempt to roll back the so-called sequester mechanism that would result in an additional $600 billion in automatic cuts.

But what neither Panetta nor congressional leaders have said is how they would actually cope with the cuts if they came to pass.

For months, the Pentagon’s top brass has toiled away on a secret strategy document that was supposed to serve as a guide to how best to cut $450 billion from the defense budget over the next decade without endangering national security.

The strategy document, which is still being debated in the Pentagon, calls for a shift away from big, expensive counterinsurgency operations like Iraq and Afghanistan, a substantially smaller Army and Marine Corps and a greater focus on China and Asia, said senior Pentagon officials.

Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, has been especially insistent in internal meetings that any cuts to ground forces must be gradual and reversible.

But the failure of the supercommittee to reach an agreement could trigger cuts that would make any strategy irrelevant and would turn the Pentagon’s meticulously crafted budget process upside down by slashing an additional $600 billion

Over the summer, Panetta told reporters that officials were not drawing up contingency plans to deal with the possibility of the cuts, putting faith instead in the supercommittee. “I’m going to give Congress the opportunity to have this committee work,” he said, dismissing a reporter’s suggestion that the Defense Department could be caught flat-footed.

Now that the committee clearly hasn’t worked, Congress still has time to reach an agreement before mandatory cuts go into effect in January 2013. A senior administration official told The Washington Post’s Federal Eye that the Office of Management and Budget “will take necessary steps to ensure that if there is a sequester, the government is prepared for it.”

But the question is when defense officials will start planning.

“The sequestration bullet is fired in January, but it doesn’t arrive until January of the following year,” Pentagon spokesman George Little said last week. “That being said, this is a large department, and we would have to plan for those cuts nearly right away.”