A recurring theme in the U.S. Senate’s hearings on the New START treaty has been the disappointment expressed by many senators over the treaty’s failure to limit Russia’s tactical nuclear warheads. Supporters of New START respond that the treaty’s exclusive focus on strategic nuclear warheads follows the pattern of all previous U.S.-Russian arms control agreements. But the critics are rightly concerned that the number of strategic warheads has fallen so low that the United States can no longer ignore Russia’s overwhelming advantage in tactical warheads.

Strategic nuclear weapons are intended to win wars by targeting major cities, military bases and other “strategic” targets. Tactical weapons, by contrast, are designed for use on the battlefield. In practical terms, strategic nuclear weapons target the Russian and U.S. heartlands, while tactical nuclear weapons were designed for use in combat in Central Europe.

During the Cold War, the United States and Russia deployed large numbers of both strategic and tactical nuclear weapons. But U.S.-Russian arms control had always focused on strategic weapons on the theory that tactical weapons were irrelevant to keeping the nuclear peace as long as both sides deployed vastly larger numbers of strategic weapons. Events on the battlefield were thought to be of little consequence if Washington and Moscow were at risk of destruction by strategic weapons.

But what was true at the height of the Cold War when both sides possessed tens of thousands of strategic nuclear warheads has become increasingly less true as both sides have reduced their strategic forces. During the administration of former U.S. President George W. Bush, the agreed ceiling on deployed strategic weapons was reduced from 6,000 to 2,200 on each side. The New START drops the ceiling even further to 1,550.

Regrettably, these deep reductions in strategic weapons have not been matched by Russian reductions in tactical weapons. By most estimates, the United States today deploys just between 200 and 300 tactical nuclear weapons in Europe, compared to Russia’s arsenal of between 2,000 and 3,000.  

The Obama administration has argued to the Senate that Russia’s 10:1 advantage in tactical weapons is militarily insignificant today and will remain insignificant even if U.S. strategic forces are cut to roughly half the size of Russia’s tactical forces as required by New START. But obviously there comes a point at which strategic nuclear reductions will be so deep — and Russia’s advantage in tactical weapons so large — that the disparity can no longer be ignored.

Incredibly, the arms control community, and even some U.S. allies in Europe, believe that the solution to this problem is to unilaterally withdraw the remaining U.S. tactical warheads from Europe, assuming incorrectly that Russia would, in turn, remove its warheads (at least those that are located in the European part of the country). The Obama administration has not embraced this solution, but it hasn’t rejected it either, promising instead to intensify consultations within NATO on the issue and calling on Russia to negotiate reductions in tactical weapons.      

Indeed, persuading Russia simply to talk about tactical weapons would be a significant achievement. The Bush administration tried repeatedly to initiate such a discussion, but Russia always demurred, insisting there was nothing to talk about until the United States withdrew all its tactical weapons from Europe, while Russia kept its weapons in that theater. Russia has become no more flexible on this issue following the advent of the Obama administration. When asked by the Senate why New START addresses only strategic weapons, U.S. Secretary of State Hillary Clinton admitted “they were not willing to negotiate on tactical nukes.”  

This inflexibility reflects a troubling reality. Russia emphatically has not embraced Obama’s vision of a world free of nuclear weapons. To the contrary, as U.S. Defense Secretary Robert Gates candidly told the Senate, “Everything we see indicates they’re increasing the importance and the role of their nuclear weapons in the defense of Russia.” Russian officials explain that the country’s conventional capabilities are much degraded since the demise of the Soviet Union, while threats to Russia’s security have increased.

These perceived threats include not just China to the East and unstable Islamic regions to the South, but also NATO to the West. In truth, NATO has served to stabilize Russia’s Western periphery rather than threaten it, but bitterness over the loss of so much of its former empire to NATO prevents Moscow from recognizing this reality.

In an environment where the threats perceived by Russia outstrip its ability to defend itself by conventional means, Russian officials see tactical nuclear weapons as the great equalizer. The United States has little to offer to persuade the Kremlin to reduce its 10:1 advantage, much less abolish these weapons entirely.  

Washington would have even less to offer if the Obama administration unilaterally withdrew the remaining U.S. tactical weapons from Europe. Proponents of this idea misunderstand the nature of the problem. In reality, Russia deploys tactical nuclear weapons to counter an imagined conventional threat from NATO.

For these reasons, New START is likely to be the last arms control agreement signed with Russia for a long time to come. Another traditional strategic arms control agreement is out of the question. Any future agreement will have to limit tactical weapons as well, but Russia appears determined to keep its tactical nuclear trump card so long as it perceives NATO as a threat. Changing that perception will take a lot more than reset buttons and unilateral U.S. concessions.