We have established fissile material transparency regimes for HEU and plutonium. We're building confidence that the HEU we're dealing with is from dismantled nuclear weapons, and that the plutonium is weapon-grade and newly produced. Somewhere in between, we have to strike a workable balance. Removing Excess Material From Weapons Programs Once we are confident what we're dealing with, the ultimate answer, of course, is permanent disposal of the material. As a start, combining nonproliferation goals with commercial activities, we're buying 500 tons of Russian HEU from weapons, blended down for use as civilian nuclear reactor fuel.
Plutonium is harder.
The first step is to keep the problem from getting worse. Several Russian plutonium producing reactors also produce needed electricity. For disposal, burning plutonium requires special fuel fabrication and specially designed or modified reactors. As a matter of policy, the US does not favor a plutonium fuel cycle, because there is very little difference between the plutonium used in weapons and the plutonium used in bombs. But there is a big difference between making new plutonium and designing reactors to burn it, on the one hand, and using existing reactors to get rid of plutonium on the other.