The U.S. missile strikes against the Islamic State jihadists in Syria and Iraq underscore a growing problem for the Defense Department. New threats are demanding the military's attention around the globe: from the rise of shadowy new terrorist groups in the Middle East to Russia's invasion of Ukraine to the rampant Ebola virus in West Africa. At the same time, the 2011 Budget Control Act caps the defense budget, which must be significantly reduced from projected levels.

What to do? Defense heavyweights are calling to lift the caps and increase spending. But given that a dysfunctional Congress would have to agree to such a major change — an unlikely prospect — it is a safe bet that there will be fewer defense dollars, at least over the next 10 years.

So where will new money for high-priority military missions come from? Simple. The Pentagon will take it from less important activities. It's a zero-sum game.

Fortunately, there is a sizable chuck of the Pentagon budget where we can safely cut back: the U.S. nuclear arsenal.

As the New York Times reported on Sept. 22, the United States plans to spend about $355 billion on nuclear weapons over the next 10 years, and up to $1 trillion over 30 years. As they say in Washington, that's real money. Yet these weapons play essentially no role in responding to today's highest-priority threats. U.S. nuclear weapons did not keep Russia from taking Crimea. They did not stop the Islamic State from rampaging through Iraq and Syria. And Ebola? Yeah, right.

A quarter-century after the Cold War, spending this much money on nuclear weapons is simply not justified. But even if it was, the harsh reality is that the country does not have the cash to pay the tab.

This summer, an independent, bipartisan federal commission co-chaired by former Secretary of Defense William Perry and retired Gen. John Abizaid called the Obama administration's plans for the arsenal "unaffordable" and a threat to "needed improvements in conventional forces."

But, of course, the Pentagon already knows this. The Navy wants 12 new ballistic missile submarines that would cost about $100 billion to build. The Air Force is seeking up to 100 new, nuclear-capable strategic bombers for at least $80 billion, as well as land-based ballistic missiles and air-launched cruise missiles. Both services know that planned spending will not cover these costs, so they are seeking additional funds — outside of their own budgets. The Senate Armed Services Committee has already approved a "National Sea-Based Deterrence Fund" to finance the construction of new submarines from another source, yet to be determined.

In the services' view, the nuclear programs are so important that someone else should pay for them.

Responding to this game of nuclear pass-the-buck, Undersecretary of Defense Frank Kendall said on Sept. 17, "at the end of the day we have to find money to pay for these things one way or another, right? So changing the accounting system doesn't really change that fundamental requirement. We still need the money and it has to come from somewhere."

Rather than hoping for a handout or creative accounting, a more pragmatic approach would be for the Obama administration to accept that the nuclear weapons enterprise is just too big and should be scaled back. Can it really be that the nation needs to rebuild essentially every missile, bomber, submarine, and warhead it's built over the last 50 years? No. It is time to get real.

"This is Obama's legacy budget," a senior administration official told the New York Times. "It's his last chance to make the hard choices and prioritize." But that doesn't mean it's an all-or-nothing proposition. We don't have to get rid of all the weapons to save a boatload of money. In fact, the United States can save billions of dollars and still keep the "triad" of delivery systems armed with the same number of nuclear warheads planned under the 2010 New START Treaty. We just need to do it in a more cost-effective way.

Here are five ideas the United States could use to save roughly $70 billion over the next decade across all three legs of the triad:

1. Build eight new nuclear-armed submarines instead of 12.

Savings: $16 billion over 10 years.

Under New START, the Pentagon plans to deploy approximately 1,000 nuclear warheads on strategic submarines. Eight fully armed submarines can meet this requirement, according to the nonpartisan Congressional Budget Office (CBO). So why buy 12? The "need" for 12 subs has more to do with how promptly they could strike their targets. More subs means you can station them closer to their targets in China and Russia for quick launch.

But the White House could relax those requirements, which are based on Cold War assumptions. Instead of forward-deploying subs, they should be kept out of harm's way, as an assured retaliatory force if ever needed. If prompt launch is required, land-based missiles can serve that mission.

2. Delay new nuclear-capable bombers.

Savings: $32 billion over 10 years.

Given the decades of service left in the current Air Force bomber fleet (B-52s and B-2s), the new bomber program can be delayed until the mid-2020s, according to CBO. Even with a 10-year delay, a new bomber would still be ready by about the time the current bomber fleet will reach the end of its service life. Moreover, the delay would allow the new bomber to incorporate technological advances made during that time. "Taking advantage of future technological developments can be particularly valuable for weapon systems that are expected to be in use for several decades," CBO states.

3. Cancel the air-launched cruise missile.

Savings: $3 billion over 10 years.

The new Air Force bomber would carry two types of nuclear weapons: a rebuilt gravity bomb (the B61) and an Air-Launched Cruise Missile (ALCM). The current ALCM, carried by B-52 bombers, is scheduled for retirement in 2030.

The new Air Force bomber – unlike the B-52 will be designed to penetrate enemy air defenses, so it needs bombs that can be dropped from above, like the B61. It does not need a standoff missile, like the ALCM, which would be shot from outside enemy airspace. If we ever do need that capability, submarine-launched ballistic missiles can do it just as well.

4. Scale back the B61 bomb life extension.

Savings: $4 billion over 10 years.

The administration plans to extend the service life of about 400 B61 gravity bombs a the cost of about $10 billion, or $25 million each, starting in 2020. This is the only U.S. nuclear weapon based in Europe, with about 180 tactical (short-range) versions stored in five NATO countries. A strategic version is stored in the United States for use on B-2 bombers.

Despite the crisis in Ukraine, the Cold War has not resumed. There is no military justification for keeping B61 tactical bombs in NATO countries. The United States can continue to reassure NATO allies and deter any nuclear weapons threat with nuclear weapons based in the United States and on submarines at sea. If B61 bombs must stay in Europe for political reasons, then they should be allowed to age out over the next decade and then retired. Let's not spend billions on a weapon that is on its way out.

5. Maintain existing land-based intercontinental ballistic missiles (ICBMs).

Savings: $16 billion over 10 years.

The Air Force is expected to decide in 2016 whether to continue to extend the life of the Minuteman III missile after 2030 or to replace it with a new one. A detailed 2014 RAND study supports extending the life of the current Minuteman III, which it found to be "a relatively inexpensive way to retain current ICBM capabilities."

The RAND report found that keeping the Minuteman IIIs in current silos is the cheapest option, a program that would still cost up to $90 billion over 39 years. In comparison, building a new silo-based ICBM would cost up to $125 billion and a mobile version (rail or road) would cost up to $219 billion.

It is hard to imagine what would justify a military requirement for a new ICBM capability beyond that offered by a life-extended Minuteman III. As the RAND report points out, only Russia is capable of attacking all U.S. ICBMs. Such an attack is highly unlikely, as Moscow could not expect to escape a nuclear response, either from ICBMs or other U.S. nuclear forces in the strategic triad. Silo-based Minuteman IIIs are survivable against all other potential nuclear adversaries, including China, and will likely remain so for the foreseeable future. 

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Proponents of nuclear weapons say that spending large sums of money to rebuild the arsenal is worth it, since the United States still faces nuclear threats from Russia and China that must be addressed. And since Moscow and Beijing are modernizing their arsenals, so should we. After all, with an annual $500 billion defense budget, spending $30 billion (or just 6 percent) on nuclear weapons is not so much, the thinking goes.

But the threats we face are changing, and so too must our responses to them.

Nuclear weapons are the dinosaurs of military hardware. This plump piggy bank should be raided to address the real high-priority emerging threats. The United States does not have to break the congressional budget deal and increase defense spending to do so. We've got the world's most expensive, most sophisticated nuclear deterrent — and the irony is that it has no deterrent effect on the most pressing conflicts we face. Surely we don't need to go out and buy new, shiny version.

Bennie J. Davis/USAF via Getty Images