Administration officials provided slightly more insight yesterday into how potential across-the-board budget cuts would be administered at the Pentagon and impact major weapons programs.

Deputy Defense Secretary Ashton Carter and White House budget chief Jeffrey Zients fielded questions from an at-times hostile House Armed Services Committee (HASC) on politically unpopular “sequestration” cuts to the defense budget. Those cuts of $1.2 trillion over the next decade–$500 billion of which would come from planned defense spending–will start next January unless congressional Democrats and Republicans can agree on an alternate plan to cut the federal deficit. The cuts–which come as a result of the Budget Control Act of 2011 and political stalemate–are opposed by both parties in Congress, the Pentagon, and President Barack Obama.

HASC Republicans, who are fighting to stop at least the first year of defense cuts from kicking in next January, planned yesterday’s hearing last month because they were upset the Obama administration had not provided more details on how sequestration would impact the Pentagon and defense industry.

The Budget Control Act of 2011 calls for the sequestration cuts to trim the same percentage from every applicable defense program, project, and activity (PPA). Yet Obama’s administration has said some parts of the Pentagon budget would be exempt from sequestration. It just announced on Tuesday, for example, that military personnel funding would not be subject to the cuts.

Zients, the acting director of the White House’s Office of Management and Budget (OMB), noted yesterday that using Congressional Budget Office estimates the across-the-board sequestration reductions could trim 10 percent from PPAs in the defense budget, and 8 percent from those in domestic account also subject to the sequestration cuts. Yet he added if sequestration kicks in next January, three months after FY ’13 starts, the cuts could be as high as 14 percent the first calendar year because the FY ’13 reductions would have to be applied over just nine months.

Lawmakers have been trying to figure out how the weapons programs in the defense budget, which has approximately 2,500 PPAs, would fare under such across-the-board cuts.

“It’s across-the-board at the PPA level, you’ve got to go PPA by PPA,” Zients testified about the sequestration reductions. “Some PPAs might have one contract in them, in which case that has to be cut. Others might have multiple contracts.”

Carter, testifying alongside Zients, added: “Sequester does apply to each and every program line item. And some programs have…both a (research and development) R&D line, and also a procurement line. And sequester applies separately to the R&D line and the (procurement line).”

He said this would result in “detailed pain” for “management of each and every one of our programs, which leads to inefficiency.”

Asked how much wiggle room the Pentagon has to work within the impacted PPAs, to apply the funding cuts as it sees fit within the accounts, Carter said he and his colleagues “are going to take advantage of any flexibility that we can find.”

“I think unfortunately there’s just so little flexibility in sequester,” he added.

Carter added more details in written testimony about how Pentagon managers of weapons programs would have to buy fewer systems if sequestration occurs.

“For example, assuming proportional cuts and (the Department of Defense’s) DoD’s current estimate of the size of the sequester, we would buy four fewer F-35 aircraft, one less P-8 aircraft, 12 fewer Stryker vehicles, and 300 fewer Army medium and heavy tactical vehicles compared with the requests in the president’s budget for FY 2013,” he wrote. “ Reductions in buy sizes will cause unit costs of weapons to rise, which will in turn demand further cuts in buy sizes.”

In cases where the Pentagon “cannot feasibly reduce the quantity of items bought,” such as with ships, it would have to delay projects, Carter wrote.

“There could be a delay of several months in the new CVN-78 carrier along with delays in the Littoral Combat Ship program and DDG-51 destroyer procurement,” he wrote.

He warned the committee yesterday about “very inefficient adjustments” that all Navy shipyards would have to grapple with under sequestration cuts.

Carter also told the HASC sequestration would not impact defense spending that is obligated if and when the cuts are made, but would apply to unobligated Pentagon funding not already put on contract.