Editor’s note: Senior Fellow Steven Pifer gave a March 25 seminar at Harvard’s Belfer Center for Science and International Affairs on “U.S.-Russia Arms Control: Prospects and Challenges.” He outlined the possibilities for future U.S. and Russian nuclear reductions and resolution of differences over missile defense, as well as the challenges that must be overcome in order to take advantage of those possibilities. Listen to the audio, view the slide presentation, and read an excerpt below.

Well Marty, first of all thanks for having this. Let me talk a little bit, I’ll draw some ideas on the opportunity, but talk a little bit about where I think Washington is on some questions such as next steps in nuclear reductions, what to do about missile defense, and a couple of other arms control issues, and then I’ll talk a little bit about some of the challenges that I think this administration faces in achieving what it would like to do.

First, just to start off with where things are now, the New START treaty was signed about three years ago. It’s now in its third year of implementation, having entered in force in February of 2011, and these are the three main limits in the treaty; 1,550 deployed strategic warheads, 700 deployed strategic delivery vehicles, and I think those are the two more meaningful limits. I should note that 1,550 is arms control math, in that 1,550 actually probably equals about 1,800 on the American side, and that’s because that 1,550 limit counts the actual number of warheads on intercontinental ballistic missiles and submarine-launched ballistic missiles, but since neither the American nor the Russian militaries keep weapons on bombers, the negotiators decided to attribute each bomber with one weapon. And the Federation of American Scientists estimate is that there are about 300 cruise missiles and bombs for U.S. strategic nuclear bombers, so in this case 1,550 on the American side is probably more like about 1,800. Now this is certainly, I think, a significant step forward on the START 1 Treaty, which allowed each side 6,000 weapons using slightly different counting rules, but I think there is still a question to be asked whether 20 years after the end of the Cold War, and 20 years after the collapse of the Soviet Union, whether these sorts of numbers are still necessary.