WASHINGTON -- At a forum in St. Petersburg earlier this month, Russian President Vladimir Putin spent much of his time mocking the Panama Papers document leak, which implicated close friends of his in shady financial transactions.
Then he took time to hit his favorite punching bag -- the United States -- with an arcane allegation and a veiled threat about the disposal of one of the most radioactive substances on the planet: plutonium.
The Americans, he alleged, were reneging on a 16-year-old deal that called for reducing Russia's and the United States' stockpiles of weapons-grade plutonium. He accused Washington of trying to preserve its ability to turn some of its plutonium stockpile back into a form usable for nuclear weapons.
"This is not what we agreed on. Now we will have to think about what to do about this and how to respond to this," Putin said. "By all indications, this will also be an irritant, which will provoke a corresponding reaction.”
The assertion, which has been denied by the United States, went largely overlooked by the wider public. But Putin’s comments caught the attention of arms-control and nonproliferation experts, as well as two U.S. senators, and serves to highlight the precarious state of affairs between Russia and the United States.
Losing That '90s Optimism
The agreement was "a sign of the ability of the two countries to work together," said Cheryl Rofer, a retired nuclear scientist at the Los Alamos National Laboratory, where U.S. nuclear weapons are designed. "I hate that we have lost the optimism of the 1990s, although not everyone thought that was a good thing then."
Plutonium has been produced in the United States and Russia for decades. In its enriched form, it is valued as fuel for nuclear weapons; in a less-pure state, it can be used to fuel power plants.
The two countries together hold the world’s largest stockpiles. The most recent inventory by the U.S. Energy Department showed the United States had around 95 tons, most of which was weapons grade.
Russia, for its part, is estimated to have around 128 tons of weapons-grade plutonium.
In 2010, Moscow and Washington recommitted themselves to a deal signed a decade earlier called the Plutonium Management and Disposition Agreement.
That deal, which was negotiated in the 1990s, called for turning a chunk, though not all, of the countries’ weapons-grade plutonium stockpiles into other forms, such as fuel for nuclear power plants.
Though the amount involved was just a fraction of the overall stockpiles -- 34 tons -- the deal has been widely viewed as a barometer of U.S.-Russian nuclear cooperation.
In the United States, the disposal process has long involved blending the plutonium with uranium and turning it into mixed-oxide fuel, or MOX, for use in power plants.
A government facility being built in South Carolina for that purpose, however, has gone billions of dollars over budget and fallen far behind schedule. The fact that uranium prices have fallen amid a global glut means there’s even less demand among nuclear-plant operators for MOX.
In February, following years of mounting criticism, President Barack Obama’s administration pulled funding for it, a decision that was praised by some experts and former Obama administration officials as "principled."
In place of the MOX plant, the U.S. government is leaning toward a "dilute and dispose" approach or "immobilization." That involves adding the plutonium to a nonradioactive substance, encasing it in glass or metal-can type containers or oil drums, and burying it at a federal waste site in New Mexico. Unlike with MOX, experts say this method could still allow for plutonium to be extracted some day and put back into weapons, though with difficulty.
This is what likely prompted Putin’s response to a question that appeared to have been planted by organizers of the April 8 St. Petersburg forum.
"Our partners should understand that, jokes aside, all their efforts to promote information products aimed against Russia are one thing, but serious issues, especially with regard to nuclear arms, are quite a different matter and one should be able to meet one’s obligations," Putin said.
The assertion drew a predictably caustic response from Dmitry Kiselyov, a television anchor and state-media boss who’s known for bombastic commentary: "America Deceives!"
The two U.S. senators representing South Carolina, whose districts would suffer the loss of well-paying jobs if the MOX project were ended, also weighed in on April 11, accusing the Obama administration of allowing Putin to take the high road.
Gary Samore, who oversaw nonproliferation and arms control efforts in the White House under both Obama and President Bill Clinton, said Putin’s remarks reflect Russian worries about U.S. intentions and capabilities that date back to the early days of the Cold War.
However, he said, by moving away from the MOX dilution effort, the Americans are essentially changing the agreement.
"Putin is right. We’re proposing to modify the agreement," Samore told RFE/RL.
"And the Russians, if they wanted to, they would be within their rights to say that they’re not going to carry through with the agreement."
The State Department, however, has denied that the United States has violated the agreement, saying it allows for the two sides to "agree on disposition methods that do not involve irradiation in nuclear reactors."
New Agreement Required?
"Accommodating any such new method of disposal...requires written agreement between the parties; we would expect such consultations on a separate agreement to begin at an appropriate later time," said Eric Lund, a spokesman for the State Department's Bureau of International Security and Nonproliferation.
"The United States remains firmly committed to the [agreement] and continues to believe that verifiable disposition of excess weapon-grade plutonium -- initially enough for 17,000 nuclear weapons -- represents an important nonproliferation and arms control step," he told RFE/RL in an e-mail.
Pavel Podvig, a Geneva-based researcher who studies Russian strategic forces, said it is likely that the Kremlin was looking at the issue as a way to put political pressure on Washington as part of its overall approach toward the United States.
"The U.S. in a difficult situation," he said in an e-mail. "Renegotiating [the agreement] would mean making some accommodations with Russia. Not impossible, of course, but may be difficult to accept."
Matthew Bunn, who runs the Project on Managing the Atom at Harvard's John F. Kennedy School of Government, agreed that if relations were better, the two sides could amend the deal, just like they did when it was renegotiated in 2010.
"I thought that was possible up until Putin made his comments," he said. "Now it would be extremely difficult for the Russians to agree to anything, given what Putin said."
Ultimately, experts say, what matters is not the increasingly likely demise of the agreement but what it says about the poisoned relationship between the two countries.
"Frankly, the way things are going, it seems to me that the agreement is nothing much at this point," Rofer said. "Mainly something to fight over."