America’s most senior foreign policy officials defended the merits of the first strategic arms control treaty to be brought before the Senate in almost 20 years last week. Secretaries Hillary Clinton, Robert Gates, and Admiral Michael Mullen went to bat on behalf of the Obama administration, which is anxious for the Senate to ratify the New START Treaty quickly, to reduce the U.S. and Russian nuclear arsenals, and win hearts in the Kremlin.

Unfortunately, the love affair is one-sided. While both Washington and Moscow have agreed to reduce their numbers of deployed strategic delivery vehicles -- which include land, sea, and air-launched missiles, long-range bombers, and submarines -- the Russians were already heading toward the newly-required limit of 700. 

So what looks like a mutual concession is actually a net loss for the United States. With negotiation outcomes like this, it is easy to see why Russia may come to love the Obama administration, but what’s in it for American security?

Prudent senators, including Jim DeMint (R-S.C.), John Barrasso (R-Wyoming), and John Thune (R-S.D.), to name a few of the most vocal, are trying to stop the rush to ratify the New START until they can be satisfied with the answer to that very question.

The new treaty will have lasting implications for global security, and deliberation on it should take months, if not longer, to ensure that the Senate can be fully informed and comfortable voting to approve or reject it.

For many senators, the vote will hinge on whether or not they can be convinced that the treaty would not prevent current or future administrations from fielding a comprehensive missile defense system. While this is reason enough to consider a no vote, it’s not the only one.

Congress required the White House to deliver a plan outlining how the U.S. will maintain its nuclear arsenal. The U.S. deactivated over 50 percent of its nuclear warheads during the Bush administration alone -- without compulsion from any binding treaty.

In a December 2009 letter to President Obama, 41 senators wrote that further reductions in nuclear weapons would be acceptable only if the administration provided a clear plan for modernizing them.

The United States is the only country that is not modernizing its nuclear arsenal, while the United Kingdom, France, Russia, China, India, Pakistan and North Korea are currently modernizing their nuclear forces, and Iran is developing theirs.

The administration recently delivered its highly-anticipated “1251 Plan,” so named for the section of the 2010 Defense Authorization Act that mandates it. Although the document itself is classified, the controversy it has created in the Senate is not. One of the greatest take-aways from 1251 comes less from what it includes than from what it leaves out. It seems to offer almost no detail on what the future makeup of U.S. nuclear forces might look like under New START.

For 25 years, the U.S. nuclear forces have rested on three “legs” to deliver nuclear warheads: sea, land, and air. Defense strategists maintain that the nuclear triad is indispensable because it denies any enemy the ability to destroy the entire U.S. nuclear enterprise in a first strike. So while the administration is clear about how many nukes and delivery platforms it’s willing to get rid of, it remains unclear about how we’ll modernize the nukes and delivery systems we intend to keep.

The 1251 Plan specifically mentions the Obama administration’s intention to build a new nuclear missile submarine. Obama’s attention to this element of the triad is appreciated, but what about those in the air and on land? In the 2006 Quadrennial Defense Review, the Pentagon stated that it planned to “develop a new land-based, penetrating long-range strike capability to be fielded by 2018 while modernizing the current bomber force.”

The 1251 plan puts off decisions for both.

The administration claims that current bombers will continue to meet national security threats over the next two decades. But Air Force officials argue that they will need a next-generation bomber by 2018, not because they expect their existing B-52 bombers to be insufficient -- though most of them are now decades older than the pilots who fly them -- but because the B-52s carry the air-launched cruise missile, which is itself nearing retirement. Compounding the problem, the 1251 plan also punts the decision to replace the ALCM.

The same problem exists for land-based nuclear forces, which are comprised of Minuteman III missiles. These are slated to be maintained through 2030, but it is unclear what happens after this. The 1251 plan also fails to mention the administration’s intention to field a system of non-nuclear ICBMs called Prompt Global Strike. The White House agreed to count PGS against the already dramatically reduced number of nuclear delivery systems allowed under the New START Treaty. This is yet another foolish concession, though judging by the looks of the plan, the administration wasn’t planning to build PGS anyway.

It’s almost as if the administration started negotiations with the only goal being to get the Russians to sign a treaty. During last week’s hearing, the witnesses made the case that, in the words of Secretary Gates, “The U.S. is better off with this treaty than without it,” but the comparison is not between this new treaty and none. The question is whether the Obama administration has negotiated a treaty better or worse than the one it allowed to expire last December.

Before they vote on the New START Treaty, Senators should probe the administration about how it expects U.S. nuclear forces to look under the new restrictions. Without a robust triad, U.S. nuclear deterrence will be devastatingly shortchanged, and so will American security.

Rebeccah Heinrichs is an adjunct fellow at the Foundation for Defense of Democracies, and a former military legislative assistant for House Armed Services Committee member Trent Franks (R-Ariz.).

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Rebeccah Heinrichs is a fellow at the Hudson Institute where she provides research and commentary on a range of security issues and specializes in missile defense and nuclear deterrence. She is also contributing editor at Providence Magazine. Follow her on Twitter, @RLHeinrichs.