Even as anti-nuke demonstrators were organizing protests around the country to commemorate the early-August anniversaries of the U.S. bombings of Hiroshima and Nagasaki in 1945, the U.S. Strategic Command held a little-publicized meeting of senior Bush administration officials on August 6 and 7 to advance plans for a new generation of nuclear arms. Proponents of the plan argue that the United States needs to tailor smaller, bunker-buster nukes in order to threaten underground nuclear facilities that may be built by such nations as North Korea and Iran. Opponents counter that manufacturing a new generation of nuclear weapons will deal a severe blow to the international arms-control regime and break down the firewall separating nuclear and conventional arms, leading to greater nuclear proliferation and the increased possibility of a nuclear war. What both sides agree on, however, is that nuclear proliferation is emerging as the single greatest threat to U.S. national security, and that America is at a crossroads in determining how to deal with it. In recent interviews, National Journal correspondent James Kitfield spoke with leading voices on both sides of the argument. C. Paul Robinson is director of Sandia National Laboratories, one of the nation's three primary nuclear weapons labs, and a former chief negotiator at the U.S.-U.S.S.R. Nuclear Testing Talks in Geneva during the 1980s. Joseph Cirincione is director of the Non-Proliferation Project at the Carnegie Endowment for International Peace in Washington, and a co-author of Deadly Arsenals: Tracking Weapons of Mass Destruction. Following are edited excerpts of their separate interviews. NJ: The one point of agreement that emerges in the debate about the Bush administration's 2002 Nuclear Posture Review is that the fundamental equation of nuclear deterrence has been forever altered by the dissolution of the Soviet Union, the proliferation of nuclear technology, and the September 11, 2001, terrorist attacks. Is that a fair assumption? Robinson: Deterrence has changed dramatically since the end of the Cold War, and we're still sorting out what that means for our nuclear posture and the future. As Russia becomes more of a friend than an enemy, we are no longer confronted with a nation that threatens our very existence. I spent many sleepless nights during the Cold War worrying about stability matrixes and first-strike, "use-them-or-lose-them" calculations. That kind of Armageddon scenario is now a distant worry. I still worry, however, about the proliferation of nuclear materials and technologies from Russia, because in many respects it's a Third World nation now, and in the Third World everything is for sale. I regret that as a nation we haven't been bolder in developing a Marshall Plan for Russia that would help it reach at least a minimum level of prosperity, which is the best antidote to that kind of proliferation. That problem is related, in turn, to what I believe is our greatest emerging threat -- rogue states armed with nuclear or other weapons of mass destruction. NJ: Given such seismic events as the dissolution of the Soviet Union and the September 11 terror attacks, doesn't it make sense to re-evaluate our strategic ability to deter aggression? Cirincione: Absolutely, and we should be taking a new look at our deterrence posture. But it's important for people to understand that this is not what the Bush administration is doing. The January 2002 Nuclear Posture Review directed the departments of Energy and Defense to begin development of new nuclear weapons, and to formulate new policies to accommodate such weapons. As a result, the nuclear weapons labs have re-established advanced-warhead concept teams to explore modifications of existing weapons, and to develop low-yield weapons and nuclear earth-penetrators that can be used against hardened targets. So the Bush administration has already decided that we need new nuclear weapons, and they are now going ahead implementing policies to reach that goal step by step. They understand that this is a very controversial decision, however, so they have adopted "salami" tactics -- they are slicing off a little bit at a time. NJ: Are the labs developing new nuclear weapons? Robinson: That depends on how you define "new." If we take a warhead off the shelf that we designed and tested in the past, and then put it on a new delivery vehicle, is that a new nuclear weapon? We will probably have to manufacture new copies because we produced only a few originally, but it is not a new design, nor will we need to test it. I can categorically state that no one is proposing returning to nuclear testing. The main point is that the world is not static. Over the past decade, nations have gone to school on our conventional military capabilities, and many of them have adopted a strategy of moving their high-value targets out of our reach by locating them in deeply buried tunnels and inside mountains. If you want to know who the main culprits are, just look at which nations are buying these huge tunnel-boring machines. You'll find that North Korea, Iran, Syria, and Libya have all built a lot of underground facilities. We keep having to relearn this lesson that the world is not stupid, and potential adversaries will constantly take actions to better their strategic position and counter our strengths. I would argue that the United States must respond by maintaining a robust deterrent against whatever is hidden in those underground facilities. NJ: Does the United States need a low-yield, nuclear bunker-buster to hold an enemy's underground facilities at risk? Cirincione: This argument that we need mini-nukes as earth penetrators is based on a lie. Every independent study done on this issue has concluded that for any target buried more than 50 yards underground, you would still need a very large nuclear warhead. Mini-nukes of a kiloton or less just don't get the job done. The big nukes you would need in order to reach a truly deep underground bunker, meanwhile, would kick up so much dirt that you would have a major problem with radioactive fallout. More to the point, there are multiple ways of attacking underground facilities using conventional weapons that would be more effective. With repeated precision strikes using conventional earth-penetrating bombs, you can bore deeper and deeper until you reach your target. You could use high-temperature thermo-baric weapons that have the advantage of destroying biological and chemical agents and pathogens. You could use precision-strike or Special Operations forces to seal the exit and entrance tunnels to an underground facility. NJ: Are there viable conventional alternatives to nuclear bunker-busters? Robinson: Our primary focus is still to accomplish this with conventional weapons, and we work hard on that problem. Nuclear weapons remain a blunt instrument of last resort. We've conducted more than 4,000 penetrator tests at Sandia since the 1960s, however, and we have a lot of data on the problem. Basically our tests show that conventional penetrators don't work very well. In the aftermath of the bombing campaign against Serbia, for instance, we discovered that we did very little to no damage against buried targets. So if we can find ways to strike these buried targets with conventional weapons, we will. If we can't, however, we need to look at what can be accomplished with a nuclear earth-penetrator that causes the least possible amount of collateral damage. That leads you away from two-stage, thermo-nuclear weapons to smaller-yield, lighter weapons with high reliability. A national command authority confronted in a crisis with the prospect of killing 40,000 people with a thermo-nuclear weapon in order to take out a bunker is probably going to decide not to. If we could design a bunker-buster that would kill an estimated 2,000 to 3,000 people, on the other hand, the answer would probably be yes if the situation was critical. Those are the weapons the Bush administration gave us the OK to begin researching about a year ago, because our scientists felt handcuffed by restrictions that were in place at the time. NJ: Would rogue nations be deterred from acquiring weapons of mass destruction, or building underground bunkers, if they knew their facilities could be reached by nuclear earth-penetrators? Cirincione: The Bush administration has adopted this arrogant attitude that the United States can take the dramatic step of developing these weapons, and there will be no international repercussions or imitators. If the most powerful nation the world has ever known says it needs a new class of nuclear weapon to defend itself against weapons of mass destruction, however, why don't other countries also need them? Why doesn't Iran, which has actually been attacked by chemical weapons? The real danger of this concept is that it blurs the lines between nuclear and conventional weapons, making nukes just another tool in the toolbox that could be used for tactical battlefield purposes. In that sense, this argument is less about deterrence than war fighting. We already have plenty of doomsday weapons in our arsenal if all we're trying to do is scare people. They are planning on using these weapons. And if the United States were to use them, it would cross a threshold that has not been breached since the Truman administration. That in turn would encourage other nations to develop and use nuclear weapons in a similar manner. That's not in the United States' national security interests. Given that we have never accepted a nuclear weapon into our arsenal without testing -- with the exception of the Hiroshima bomb -- the path the Bush administration is on also greatly increases the likelihood that the United States will return to nuclear testing, which would be a terrible blow to the nonproliferation regime. NJ: Will developing a nuclear bunker-buster likely lead to new testing? Robinson: I don't think we will need new testing, because the warhead we are talking about has already been tested. As I said earlier, we would need to start production of new warheads again. I continue to abide by my statements that we're a long way from going back to nuclear tests. Having said that, I helped write the safeguards that were written into the Comprehensive Test Ban Treaty ratification protocols, which essentially stated that the president of the United States would withdraw from the treaty and return to testing if a serious problem developed in the U.S. nuclear arsenal that required testing for a solution. The point I'm making is, the United States has been willing to abide by these treaties only as long as they do not conflict with our essential security posture. NJ: How do you respond to arms control experts who charge that remanufacturing a new class of nuclear bunker-busters violates the Nonproliferation Treaty, which commits the United States to "pursue negotiations in good faith on effective measures relating to the cessation of the nuclear arms race" and "to nuclear disarmament?" Robinson: I was in the Reagan administration when we debated what exactly was meant by Article VI of the NPT, and it seems to me that the end state of total nuclear disarmament that the treaty envisions will occur around the same time that the lamb lies down with the lion. And I always argued that even at that point, the lamb still won't get much sleep. In truth, I believe that the NPT was intended more as a confidence-building measure than as a real arms control treaty that we were willing to bet our country's survival on. We would never have negotiated an arms control treaty with the ridiculous verification inspections by the International Atomic Energy Agency prescribed in the NPT, which missed the programs in Iraq and Iran and even Israel. Where has the IAEA spent the most money in terms of inspections? In Germany, Canada, and Japan. Why? Because it is a confidence-building measure among friendly countries eager to prove they are not violating it. It was never set up to catch cheaters. That's why I disagree with people who infer that the NPT is a real arms control treaty. It's not. NJ: Is the NPT more a gentlemen's agreement than an arms control treaty? Cirincione: That's just nonsense. President Bush just negotiated a treaty on strategic nuclear weapons with Moscow that has no verification regime, yet he still insists that it's vital to our national security. The NPT was the beginning of what became a comprehensive, interlocking network of treaties, agreements, and enforcement mechanisms designed to stop the proliferation of not only nuclear weapons, but also chemical and biological weapons. It established a legal and diplomatic framework for a non-nuclear future, and it has worked. Instead of the 20 to 25 nuclear nations that President John F. Kennedy predicted, we now have eight worldwide. That's still eight too many, but that's not a bad track record. As the nuclear states continue to move toward ever-smaller arsenals as called for in the NPT, we will continue to devalue nuclear weapons globally. That's the whole crux of the matter: Given our overwhelming conventional military superiority, the United States is more secure in a world where nuclear weapons are devalued and dwindling as opposed to a world where we and others are developing new nuclear weapons for new uses. Now, there are certainly enforcement problems with the nonproliferation regime, as there are with all international and national laws. Does that automatically mean the laws are useless? No, it means we need to get better at enforcement and adapting them to new circumstances. There's no question that we need to toughen IAEA inspections and to take a fresh look at some of the fundamental tenets of the nonproliferation regime. Some people in the Bush administration think the first thing you do in such a circumstance is tear down the bridge you're standing on. I argue instead that we need to strengthen the bridge. NJ: Do you credit the NPT for slowing the march of nuclear proliferation? Robinson: I think the North Atlantic Treaty extending our nuclear umbrella to our European allies did much more to prevent nations from going nuclear than the NPT, and will do more in the future as more Eastern European nations join NATO. That's why I argue that we should also extend that umbrella further from Japan to encompass Southeast Asian nations such as South Korea, Thailand, Singapore, and the Philippines. NJ: Do you ever worry that the United States' aggressive strategy of pre-emption, coupled with our overwhelming conventional military capability, might convince some nations that nuclear weapons are their only deterrent against us? Robinson: The National Security Strategy lays out very carefully the conditions that might prompt pre-emption, which are basically limited to those instances when the threat of many American deaths is imminent and you have the nexus of rogue states with weapons of mass destruction and links to terrorists. Having said that, a friend of mine recently pointed out that the United States was not deterred from going to war by Iraq's supposed arsenal of chemical and biological weapons. We haven't responded nearly as quickly to North Korea's announcement that it has nuclear weapons. Some people could draw the lesson that the United States can be deterred by nuclear weapons, but not by chemical or biological ones. I can't argue with that conclusion.