When the Soviet Union splintered two decades ago, one of the biggest U.S. worries was how to ensure that the vast Soviet arsenal of nuclear weapons was kept secure.
The American response was the Cooperative Threat Reduction program of 1992. The U.S. provided money and expertise to lock down and track weapons of mass destruction and make sure they stayed out of the hands of rogue regimes or terrorists.
The program has been hailed as a great success, with thousands of Soviet nuclear weapons dismantled over the years.
But Russia said this week that it's not planning to extend the program, a move that appears to be part of a broader effort by Moscow to block U.S. aid programs that operate on Russian soil.
Russian officials say they no longer need U.S. help to secure their nuclear stockpile. But Americans say the two countries should keep working together, not just in the former Soviet Union but around the world.
The program is often called the Nunn-Lugar program, after the two U.S. senators who sponsored it, Sam Nunn, who was a Democratic lawmaker from Georgia, and Richard Lugar, a Republican from Indiana who was defeated in a primary earlier this year.
After the 1991 Soviet breakup, weapons were stockpiled in seven newly separate countries, from Russia to Kazakhstan, with governments that didn't have the money or the expertise to secure them.
The program wasn't cheap — about $500 million a year — but nuclear experts say it was a bargain.
"We have helped Russia destroy more nuclear weapons than we probably would have been able to do in an actual nuclear war with Russia," says Jon Wolfsthal, an expert on nuclear proliferation at the Monterey Institute for International Studies.
The program is credited with deactivating more than 7,500 Soviet nuclear warheads and destroying more than 900 intercontinental ballistic missiles.
The program has been extended twice and is due to expire in June of next year.
U.S. officials were surprised when they heard news reports from Moscow saying that the Russians weren't willing to renew the program. U.S. State Department spokeswoman Victoria Nuland says the talks with Russia are still going on.
"They have told us that they want revisions to the previous agreement," she said. "We are prepared to work with them on those revisions, and we want to have conversations about it."
The talks are, however, taking place in an increasingly tense environment.
The Kremlin recently announced it would no longer allow the U.S. Agency for International Development to keep working in Russia.
Opposition To American Aid
Under President Vladimir Putin, Russia has become less and less willing to be seen as accepting outside aid — especially from the United States.
Wolfsthal says he thinks the balky stance of the Russian officials is mostly traditional Russian negotiating behavior.
"They think that we want this more than they do, and they want to strike as good a bargain as they can, and one of the best ways for them to do that is to threaten to cut the whole thing off unless they get what they want," he says.
Nunn, meanwhile, says he thought Russian pride would eventually make Russian leaders uneasy about accepting U.S. aid.
"I have no objection whatsoever to Russia spending their own money," he says. "They have oil and they have a lot different financial situation than they did in the early 1990s, and frankly, we have a lot different financial situation also, so that part doesn't bother me."
What does bother him, Nunn says, is the prospect that 20 years of shared experience and expertise could be squandered if Russia and the U.S. stop working together.