Olive/Getty Images A nuclear power plant near Liverpool, England

Chances are good that if you’ve switched on a light in the United States in the last 20 years, you can thank a retired Russian nuclear warhead for lighting up the darkness.

In 1993, the Russian Federation, still emerging from the ruins of the Soviet Union, negotiated a deal with the United States to turn 500 metric tons of highly-enriched uranium from Russian nuclear warheads into fuel for American power plants. For two decades, “Megatons to Megawatts” has been a seminal—and sometimes lonely—bright spot in nuclear non-proliferation efforts, converting enough weapons-grade uranium to make 20,000 nuclear bombs into energy for American homes.

“Megatons to Megawatts” expires in December this year, an artifact from an era when relations between the two rivals were much more congenial than they are in 2013. With Moscow and Washington at odds over a swarm of issues that range from Edward Snowden to Syria to basic democratic principles, it’s hard to imagine the old adversaries coming to such an arrangement now.

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“Certainly the politics are very different today,” said Steven Pifer, director of the Arms Control Initiative at the Brookings Institution. Megatons for Megawatts came on the heels of two groundbreaking arms control initiatives, the START 1 and START 2 treaties. Still reeling from the collapse of the Soviet Union, Russia was left with thousands of retired nuclear warheads and few sources of income. The program “injected money into Russia when the economy was in free fall,” Pifer said. Rather than needing to find a way to store the highly enriched uranium in the retired bombs, the material could be diluted and sold to the United States, providing $13 billion for the Russian economy over 20 years.

Megatons for Megawatts was a good bargain for the U.S., too. According to the Energy Information Administration, nearly ever nuclear power plant in the U.S.—which supply a fifth of the country’s electricity—has used fuel originating in the program. And for the world as a whole there was a significant reduction of fissile material, equivalent to about a third of all highly enriched uranium in existence today, meaning there is that much less material for a nuclear weapon floating around for a band of terrorists or a rogue state to get its hands on. “The elimination of 500 metric tons of [highly enriched uranium] in the Megatons to Megawatts program was a big deal,” Pifer said.

The Federation of American Scientists estimates there are 17,300 nuclear weapons still in existence, mostly in the US and Russia, but the Russian-American relationship isn’t the only thing standing in the way of re-upping for another 20 years of Megatons for Megawatts. For one thing, it’s unclear if the Russians actually have enough weapons ready for retirement to fill another 500 metric ton order—the actual size of nuclear stockpiles are classified in both countries.

Furthermore, in 2013, a bilateral agreement with the U.S. may not be the great deal for Russia that it was in 1993. Though nuclear power in the US is on the ropes, under pressure from high operating costs, cheap natural gas and subsidized renewables, it’s a growth industry elsewhere, like China, with its 17 nuclear reactors in operation, 29 under construction and more yet in the works, according to the World Nuclear Association. Two decades after Russia sealed a disarmament agreement directly with the U.S., Moscow may find a better deal selling nuclear fuel to Beijing,

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