MARY LOUISE KELLY, HOST:
Here are a few words you hope never to hear in the same sentence - nuclear reactor and exploded. Confirmation that a small reactor off the coast of northern Russia had indeed exploded came late this past Sunday. At least five people are confirmed dead. The explosion apparently happened during tests of a new nuclear-propelled missile, which is raising questions about that missile and about Russia's ambitions for its weapons arsenal. To try to answer them, let's bring in David Sanger of The New York Times.
Welcome back, David.
DAVID SANGER: Great to be with you again, Mary Louise.
KELLY: How bad a nuclear accident was this?
SANGER: Well, Mary Louise, it was at least bad enough to kill five people and perhaps more. Here's what we think happened. The Russians have been experimenting with a new cruise missile, which NATO codenames Skyfall. This missile is not only supposed to carry a nuclear weapon, it's supposed to be powered by a nuclear reactor. And that reactor is supposed to let it go anyplace in the world. The fuel would be fundamentally limitless. And this is a very difficult technology. The United States tried it in the '50s and '60s and gave up after one disaster after another. And now the Russians are learning some of the same thing.
KELLY: Meanwhile, Vladimir Putin has talked about this new class of weapons that Russia's been building. We've got tape of him talking about this last year. This is a - an interpreter delivering his version of a State of the Union speech.
(SOUNDBITE OF ARCHIVED RECORDING)
PRESIDENT VLADIMIR PUTIN: (Through interpreter) We've developed the new strategic weapons that don't use ballistic trajectory at all, which means that missile defense will be useless against it.
KELLY: Missile defense will be useless. If this is indeed the missile suspected of being involved in this nuclear accident, David Sanger, what might this incident tell us about Russia and its weapons ambitions?
SANGER: Well, in the course of that State of the Union address that he gave in 2018, President Putin showed off a fairly ambitious-looking animation. And the animation was intended to show a few different kinds of weapons. One of them was an undersea weapon which people believe would be a - basically an undersea drone.
Two of the other weapons were in the air. One of them was supposed to move at five times the speed of sound. The other one was supposed to be the Skyfall cruise missile. And cruise missiles move in a zigzag pattern. They stay largely within the atmosphere, and they're very hard for missile defenses to counter because they don't follow a predictable path.
KELLY: Also worth mentioning, such missiles aren't banned by the one major arms treaty still in place between the U.S. and Russia.
SANGER: That's right. And the key phrase there that you use, Mary Louise, was the one major. Last month if we were having this conversation, there would have at least been two treaties. But one of them, the INF treaty - the Intermediate Nuclear Forces Agreement - the United States left it on August 2, claiming accurately that the Russians were cheating on it.
All of the new weapons that Putin showed are not covered by existing treaties, and I think that he has been working hard to come up with technologies that wouldn't be covered by them and I think has no intention of signing any treaties that would be, unless the U.S. gave up missile defenses.
KELLY: So big picture, does this suggest that this wasn't the scenario that Russia was hoping for with this particular test, but that they are working hard to try to develop a new class of weapons that will be harder for the U.S. to counter?
SANGER: One way to look at it is this is just shakedown cruise stuff, and they had a tragic accident. The other way to look at it is that they're trying to develop a technology that others have tried and failed, and they'll have to give this up. But I think the big lesson is this, that we're in a new arms race, that it's not going to look like the old Cold War arms race. It's not about building sheer numbers. It's about having weapons that you can't defeat. It's about combining these weapons with cyber technology, with anti-satellite technology so that you have a range of weapons that the adversary cannot stop, and that that has become the new battleground, not sheer numbers.
KELLY: David Sanger, he is national security correspondent at The New York Times.
SANGER: Thanks to you.
(SOUNDBITE OF NICK BOX'S "THOUGHTS") Transcript provided by NPR, Copyright NPR.