In his first inaugural address, President Obama made this pledge: "With old friends and former foes, we will work tirelessly to lessen the nuclear threat, and roll back the specter of a warming plant." In his second address, the president again returned to climate change -- but dropped the nuclear threat. He didn't mention it once.  

Perhaps it is not fair to read too much into this. But there's been a strange silence about nuclear arms control lately. It has largely been ignored in the public discussion of priorities for the president's second term.

No doubt, there will be plenty of arcane details discussed at confirmation hearings for Sen. John Kerry and Sen. Chuck Hagel to be secretaries of state and defense, respectively. But what about the president? Does he still believe in his vision of "a world without nuclear weapons," described in the Prague speech of April, 2009?

Last year, election campaigns in the United States and Russia meant a lost year for nuclear arms control. Now, the campaigns are over, but the prospects are still cloudy, at best.

The weapons haven't gone away just because we stopped talking about them. The United States and Russia still have the largest nuclear arsenals in the world. While there are serious concerns about Iran and North Korea, about India and Pakistan, among others, keep in mind the huge differences in scale. The arsenals of the United States and Russia are about 16,200 warheads, while the other countries in the world are estimated to have about 1,100 nuclear weapons combined.

The president's first-term New Start treaty with Russia established very important verification procedures, but it provides for only modest reductions in the two nation's stockpiles, down to 1,550 warheads on each side, after seven years. It was a stepping stone, but ought not to be Obama's last step.

A lot of thought has gone into the next moves, both inside the administration and outside. Scholars and non-government strategy groups have spent months coming up with detailed, useful reports about how to rein in the nuclear danger. This informal staff work is valuable, and ready.

For a roadmap of the possibilities, see "The Opportunity: Next Steps in Reducing Nuclear Arms," by Steven Pifer and Michael E. O'Hanlon of the Brookings Institution. The book is a sober, fact-filled assessment of the choices that Obama now faces. "Why pursue nuclear arms control when the cold war is more than twenty years in the past?" they ask. "Arms control is not and should not be considered an end in itself. It is a tool that, properly applied, can strengthen and enhance the security of the United States and America's allies." They offer seven arguments for additional nuclear arms control. Among them: to put under legally-binding, verifiable treaty agreements all those nuclear warheads which are currently outside the treaty system, both in the United States and Russia.

Another solid piece of work on this theme is the report "Trimming Nuclear Excess: Options for Further Reductions of U.S. and Russian Nuclear Forces," by Hans Kristensen of the Federation of American Scientists, published last month. Kristensen says, "There are indications that, although U.S. and Russian reductions are continuing, both countries are becoming more cautious about reducing further… both countries are now investing huge sums of money in new nuclear weapon systems that are designed to operate toward the end of the century. Unless new unilateral reductions take place or significant arms control agreements are reached, large nuclear forces could be retained far into the future."

Yet another significant source of thinking about a new agenda is contained in Global Zero's U.S. Nuclear Policy Commission report of last May. The commission was chaired by retired Gen. James Cartwright, included Hagel, and the study was directed by Bruce Blair. The report provides a series of illustrative steps in which the United States could reduce its nuclear arsenal to a maximum of 900 total nuclear weapons, while increasing the warning and decision time. The report also envisions bringing in all the nuclear weapons powers for the first time for multilateral negotiations to limit nuclear arms.

But with all this intellectual firepower, why has the debate seemed to grow silent?

Vladimir Putin is one reason. Since returning to the Russian presidency last year, he has championed new laws intended to push back against pro-democracy protestors in the streets, and in some cases, against American influence on Russian society and politics. Most damaging of all, Putin rammed through the Russian legislature a bill that forced the abrogation of a bilateral agreement, which had just come into force a few weeks earlier, on adoption of Russian children by American parents. This was Putin's angry retaliation for the Magnitsky Act, legislation approved by the United States Congress and signed by the president that imposed visa and other restrictions on Russians believed to be involved in serious human rights abuses. The adoption bill seems to mark a nadir in recent relations between the two countries. Mistrust is again on the rise--corrosive mistrust.

One can only imagine the chorus of protests that Obama would face with another arms control treaty. It does not take a cynic to envision a Republican senator asking the question: If the Russians could so abruptly abrogate an agreement on adopting children which they negotiated carefully over a year's time, how can they be trusted to stick to an agreement on nuclear weapons? It is a very tough question to answer.

My own response to that is that nations don't have friends, they have interests. A treaty is a contract, and contracts are made to protect interests. It is in the interest of both the United States and Russia to avoid a nuclear catastrophe--an accidental launch, a loose nuke, a terrorist attack. Both countries possess thousands of nuclear weapons that are still not covered by any treaty, not subject to verification nor, in some cases, is the quantity even known to each other. These excess weapons are a legacy of the Cold War and really serve no useful military purpose today. Getting these warheads sorted out and locked down is in our national interest. Doing so should not be seen as a favor to Putin.

However, arms control does not exist in isolation from other issues roiling the relationship. It is hard to negotiate with Moscow or sell to Congress an agreement on something so consequential and difficult if there is an abundance of mistrust. Obama and Putin may need to reset the reset with Russia before they can do anything more on nuclear arms control.

I think Obama personally wants to do more, but much depends on Putin and how he sees Russia's interests when it comes to strategic weapons. In Moscow, there are some who think that despite the steady retirement of aging weapons from the Cold War years, Russia can modernize its arsenal, and doesn't really need another arms control agreement with the United States. For Putin, the question really boils down to whether he wants to spend heavily on that modernization, and whether he can sustain that resource drain, given other demands. The Russians are talking about building a massive new liquid-fueled, multiple-warhead intercontinental ballistic missile. Do they really need it? Putin's actions since returning to office suggest he is heading toward a Fortress Russia, a more isolated, go-it-alone approach.

But these things tend to oscillate, and could swing in the other direction yet again.

Although Obama didn't mention nuclear danger in his speech, he has a very full inbox on his desk of possible initiatives and decisions.

The president's Nuclear Posture Review of 2010 must be implemented. For more than a year, staffs have been working on memos about how to execute the decisions from that document and what guidance the president ought to give the Pentagon. His decisions could set a path for future reductions in nuclear arsenals--potentially deep cuts, if he choose to go that way. But so far there has been only silence from the White House about this.

The president has called for ratification of the Comprehensive Test Ban Treaty, but he did not submit it to the Senate in his first term. Many of the technical objections raised in 1999 when the Senate failed to ratify the treaty have been overcome in the stockpile stewardship program. Is the president ready to spend some political capital and wage a fight for the treaty?

Missile defense remains a thorny obstacle to arms control negotiations with Russia. The president could apply some creative thinking here to overcoming Moscow's concerns, which are largely focused on later stages of the U.S. missile defense plan, five to seven years from now. The near-term problem is that no negotiations on reducing offensive weapons will get to first base until there's some common understanding on missile defense. If the U.S. missile defense program is not a threat to Russia's strategic deterrent, how do we make that case in a persuasive way that permits arms control talks on offensive weapons to move ahead?

As I have argued earlier in FP, the president ought to consider a bilateral agreement with Russia to take nuclear-armed missiles off launch-ready alert.

And it is worth keeping in mind that two large categories of nuclear weapons are still uncovered by treaty-- the smaller or tactical nuclear warheads in Russia, and the strategic warheads kept in reserve since the end of the Cold WAr by the United States. No one knows precise numbers, but there are several thousand of these weapons that should be counted, verified and brought under treaty. That's a worthy goal for a second term.