President Putin of Russia, speaking at a meeting with journalists, raised concerns about the possible changes in U.S. plutonium disposition plan. According to the official transcript of the meeting, he made the following comments:
[...] back in the early 2000s, the Americans and we agreed on destroying weapons-grade plutonium. [...] Each side had 34 tonnes. We signed this agreement and settled on the procedures for the material's destruction, agreed that this would be done on an industrial basis, which required the construction of special facilities. Russia fulfilled its obligations in this regard and built these facilities, but our American partners did not.
Moreover, only recently, they announced that they plan to dispose of their accumulated highly enriched nuclear fuel by using a method other than what we agreed on when we signed the corresponding agreement, but by diluting and storing it in certain containers. This means that they preserve what is known as the breakout potential, in other words it can be retrieved, reprocessed and converted into weapons-grade plutonium again. 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. [...] [O]ur partners should understand that [...] serious issues, especially with regard to nuclear arms, are [where] one should be able to meet one's obligations.
The comment refers to the recent U.S. administration decision to discontinue construction of the MOX Fuel Fabrication Facility (MFFF) at the Savannah River Site and to begin conceptual design of the dilute and dispose option, which would not involve irradiation of the disposed plutonium. However, the U.S.-Russian Plutonium Management and Disposition Agreement (PMDA), which was completed in 2010, specifies that the United States will dispose its plutonium by burning it in light water reactors (Article III.2). Changing the disposition method will require formally amending the agreement, which cannot be done without Russia's consent. Supporters of the U.S. MOX program have used this fact to argue that the MFFF construction should continue.
A number of prominent U.S. experts have noted in a letter to the Secretary of Energy that this change would not be unprecedented. Indeed, the initial agreement, reached in 2000, was amended in 2010 to accommodate the changes in plutonium disposition plans in Russia and the United States. However, Russia may choose to argue that the dilute and dispose option that the United States is planning to pursue is not entirely compatible with the PMDA's intent. The original 2000 agreement assumed that plutonium would be either consumed in a reactor or immobilized in containers where it would be protected by a radiation barrier (Article III.2 and Annex on Technical Specifications, Section II).
This appears to be exactly the argument that was made by the Russian president in his remarks. It should be emphasized, however, that he did not say that Russia will reject the U.S. proposal to amend the PMDA (which would be made once the new disposition method is determined). It is very likely, however, that Russia will use this issue to apply certain political pressure on the U.S. administration.