The chairman of the Joint Chiefs of Staff, Adm. Mike Mullen, is fond of saying the “the most significant threat to our national security is our debt.” He’s wrong. The most significant threat to our national security is the debt-limit deal Congress approved last week.

The all-cuts, no tax increases deal was a significant victory for fiscal conservatives. Now it has become clear what the price of that victory was — deep, destructive cuts in national defense.

According to the White House, the first tranche of cuts will reduce defense spending by about $350 billion over the next 10 years. If enacted, these cuts would come on top of the more than $400 billion already cut from defense during Obama’s first two years in office — bringing the total reduction in defense spending to more than $750 billion. This is not cutting defense, it is gutting defense.

It gets worse. If the “super committee” established under the bill does not reach agreement on a second tranche of spending cuts, the Pentagon will get hit with another $600 billion in automatic cuts. This means the Pentagon could see its budget contract by more than $1.3 trillion. With reductions of this magnitude, America could not maintain its position as the world’s sole unquestioned superpower.

What can be done to stop this catastrophe in the making? Defense hawks on Capitol Hill tell me that in 2012 and 2013 they can mitigate some of the damage by cutting funds from other “security” accounts — such as homeland security, intelligence, veterans, State Department and foreign aid — to protect defense. But there is not enough money in these accounts to make defense whole. After the first two years, they say, there is a global cap on all discretionary spending — which means the pool of programs that can be targeted to protect defense expands.

The second tranche is a much bigger challenge. On paper, the automatic cuts are nearly equally divided between defense and domestic spending. The problem is Democrats succeeded in exempting many of their most cherished programs from the threatened sequester — everything from refundable tax credits to education, federal highway programs and even airport grants. If Republicans won’t accept tax increases when the special committee meets, Democrats can simply walk away and pocket deep defense cuts while protecting most entitlements and many of the discretionary programs they care about. Indeed, some have suggested that the Democrats’ default position will be to let the special committee fail and allow the automatic defense cuts to kick in.

But Republicans have a secret weapon: The Democrats failed to exempt Obamacare. According to Sen. John Barrasso (R-Wyo.), “There are at least 15 provisions of the Obama health care law that will find themselves subject to this trigger if the committee is not able to come up with other cuts.” That means if Democrats want to gut defense, they may have to accept deep cuts for prevention programs, community health centers, grants to help states set up insurance exchanges and co-ops, and other key Obamacare provisions.

That changes the dynamic of the special committee’s negotiations dramatically. If Republicans refuse to raise taxes or cut defense as part a deal, Democrats will have to choose between deep cuts in entitlement spending or deep cuts to Obamacare. Indeed, with cuts to Obamacare scheduled to automatically take place, the real challenge may be persuading some Republicans not to simply walk away and let the trigger kick in. A sizable number could decide that $600 billion in defense cuts is a price worth paying to defund Obamacare.

Therein lies the deeper problem: The fact that Republicans agreed to put $1.36 trillion in defense cuts on the chopping block shows just how much the GOP consensus behind a strong national defense has eroded. It is essential that House Speaker John Boehner and Senate Republican leader Mitch McConnell support the efforts of GOP hawks to replace the first tranche of defense cuts with cuts in other kinds of spending — and appoint to the special committee Republicans who understand that holding the line on defense is just as important as holding the line on tax increases.

If they fail do so, the results could be disastrous. As Gen. Martin Dempsey, President Obama’s choice to be the next chairman of the Joint Chiefs of Staff, has warned, cuts of this magnitude would be “very high risk.”

The war on terror is far from over. We face potential conflicts with Iran, North Korea, Yemen and Somalia. And as we learned on Sept. 11, 2001, new threats can emerge suddenly to surprise us. Despite this, Washington is once again prematurely claiming a “peace dividend” — except this time without the peace.