Washington (CNN) -- Vowing that he "came into this job to fight," Secretary of Defense Leon Panetta said he intends to make sure "some common sense prevails" as Congress works to find more ways to reduce the national debt.
Panetta, just a little over one month on the job since replacing Robert Gates, held his first Pentagon news conference Thursday.
Most of the briefing centered on questions about the debt-ceiling deal hammered out last weekend and signed into law Tuesday by President Barack Obama.
The deal requires nearly $1 trillion in cuts right away. The Pentagon's share of that is about $400 billion according to a senior defense official.
The Defense Department has been working to find that $400 billion in budget savings since last April and Panetta said Thursday that cutting $400 billion is "manageable and that we can achieve it in a way that will protect our national defense."
The problem now, Panetta indicated, is twofold.
The so-called congressional "super committee" created by the debt deal to hammer out another $1.5 trillion in cuts or tax increases could mandate deeper defense cuts. And if the committee can't reach an agreement by late November, the debt deal calls for "sequestration" -- mandatory across-the-board reductions that would mean another $500 billion in defense cuts.
"God willing, that would not be the case -- but if it did happen, it would result in a further round of very dangerous cuts across the board, defense cuts that I believe would do real damage to our security," Panetta said. "It is an outcome that would be completely unacceptable to me as secretary of defense."
Asked if that meant that across-the-board defense cuts would prompt him to resign, Panetta said, "I didn't come into this job to quit. I came into this job to fight. And my intention is to fight to make sure that hopefully some common sense prevails here."
Panetta recalled his time in Congress, where he served nine terms as a member of the House from California. "I was involved in the conference on Gramm-Rudman. I know what -- I know what sequestration is all about," Panetta said, referring to a budget-control law passed in the mid-1980s that also used sequestration as a last-ditch measure.
"In the past, Congress made the decision not to proceed with Gramm-Rudman, not to proceed with sequester, because the results would be so damaging. And so every time the trigger was about to take effect, it was postponed."
Panetta said Congress must start looking at more than discretionary budgets to deal with the deficit and start looking at entitlement programs and raising taxes.
"If you're going to deal with those size deficits, you've got to look at the mandatory side of the budget, which is two-thirds of the federal budget, and you also have to look at revenues as part of that answer," said the defense secretary.