The Fissile Cliff - By Tom Z. Collina

Fiscal reality is catching up with the Pentagon. On Wednesday, the White House Office of Management and Budget directed the Defense Department to start planning for life after the fiscal cliff. Specifically, defense planners must now come up with $500 billion in spending cuts over the next decade.

A good place to start is the U.S. nuclear weapons budget, which at roughly $31 billion per year supports a nuclear stockpile of 5,000 weapons. We don't need that many, according to the Pentagon, and the White House is preparing new guidance on how low we can go. But even before that decision gets made, there is one glaring example of a project that is ripe for pruning: the B61 bomb.

The B61 is mainly based in Europe -- a so-called "tactical" nuclear weapon designed to be used against invading conventional forces -- and the Pentagon and the National Nuclear Security Administration (NNSA) want to extend its service life until 2040 or so. This may sound simple, but it's an expensive proposition. NNSA estimates that the program will cost about $7 billion and produce its first rebuilt bomb in fiscal year 2019. But in July, a Defense Department review projected that the program would cost $10.4 billion and would not produce the first rebuilt bomb until fiscal year 2022. With 400 bombs reportedly planned for upgrades, each B61 would cost roughly $25 million.

When this was first revealed in July, Sen. Dianne Feinstein (D-CA), who chairs the Senate Appropriations subcommittee that controls NNSA funding, said the new price tag requires the NNSA to find billions of additional dollars "at a time when budgets are shrinking."

But cost is far from the B61s only challenge. The B61 life extension program, or LEP, has become an unaffordable solution to a problem that does not appear to exist.

The United States currently keeps about 180 B61s in Europe to assure allies of the U.S. commitment to NATO. However, U.S. and NATO military leaders acknowledge that it is U.S. strategic forces -- that is, the larger nuclear weapons based in the United States and on American submarines -- that provide the ultimate guarantee of NATO security, not the tactical versions of the B61 bomb stored in bunkers on European air bases.

Some NATO members, such as Germany, have called for the B61 to be removed from Europe. It is also possible that a future agreement between Russia and the United States to account for and reduce tactical nuclear bombs would require that the United States remove B61s from NATO. This raises the awkward possibility that most B61 bombs might not be needed a decade from now, when the proposed rebuilding program would be complete.

That issue aside, it is not clear why the bombs need a full-scale life extension now. The Pentagon and NNSA have asserted that B61 bomb parts need to be replaced soon or the bombs would no longer meet operational requirements, such as the ability to produce a specific explosive yield. NNSA had planned to complete the program by 2022, but the Pentagon review suggests this deadline would be missed by a few years.