Through the Cold War the United States and Russia built vast nuclear arsenals, creating a balance of terror that gripped the world.
Now in a twist, talks on dismantling some of these weapons have become the main issue binding the two sides — and arms control is at the top of the agenda for President Barack Obama's 2 1/2-day visit to Moscow starting Monday.
Officials and experts on both sides say ongoing talks about a new arms control treaty might form the foundation of a new, less rancorous relationship between Washington and Moscow. And cuts in nuclear arsenals could also give the U.S. and Russia added credibility as they try to persuade Iran and North Korea to abandon their nuclear programs.
The specific challenge both countries face: Negotiate a successor pact to replace the 1991 Strategic Arms Reduction Treaty, or START I, that expires on Dec. 5. The 500-page document contains a web of measures seen as crucial for both nations to keep a wary eye on one another's nuclear stockpiles.
Both sides say the aim is to cut arsenals from more than 2,000 each to as low as 1,500 apiece. Between them, the two countries control 90 to 95 percent of the world's nuclear weapons.
At the Moscow summit, Obama and Russian President Dmitry Medvedev are expected to announce their commitment to reaching a deal, although it is not clear if negotiators can meet the December deadline.
'Troubled' relationship
Reaching a new arms pact, many experts say, would not only reduce the threat of nuclear conflict, they could also improve damaged U.S.-Russia ties.
"If we have a successful negotiation, that will put a big positive on a relationship that has been pretty troubled over the last five or six years," said Steven Pifer of the Brookings Institution think tank, a former U.S. diplomat and veteran of previous arms control talks.
Both countries also need to prove to the rest of the world that they are serious about disarmament and lowering the global threat of nuclear war.
"It's important that they are reducing their nuclear arsenals if they are going to have any credibility when they are making argument to other countries not to acquire nuclear weapons," Pifer said.
While both the Kremlin and the White House have say they want a new treaty, meeting the deadline will be hard. During Cold War times, pacts like START 1 took legions of diplomats and military experts years to draft.
The talks are further complicated by U.S.-Russia relations, which sank to a post-Cold War low last year following Russia's war with the former Soviet nation of Georgia.
European missile shield
Another roadblock has been U.S. plans for missile defense in Europe. Former U.S. President George W. Bush pushed the project, but Obama has put it on hold until he's convinced it is cost-effective.
Russia wants the U.S. anti-missile system to be scrapped altogether, saying it could pose a threat to the strategic nuclear balance if START is expanded.
The U.S. insists that the missile shield is aimed at potential threats from Iran, but Moscow fears it would give the U.S. the capability to launch a nuclear strike against Russia without fear of retaliation.
The fewer missiles Russia has, they point out, the easier it would be for any anti-missile system to intercept them.
But Medvedev said in June that the White House must address the Kremlin's concerns if it wants a new arms control deal.
The Obama administration doesn't appear enthusiastic about the missile defense system. Neither does it want to be seen knuckling under Kremlin pressure.
"Without Russian pressure, the plan for missile defense in Europe will likely die on its own," said Pavel Podvig, a research associate at Stanford University's Center for International Security and Cooperation. "But if Russia tries to exert pressure, it will have the opposite effect."
There are signals, in fact, that both sides are inching toward a compromise on missile defense.
Earlier this month, U.S. Defense Secretary Robert Gates told senators that Moscow was increasingly concerned about the threat of Iranian long-range missiles. That, he said, could lead to an agreement for Russian participation in the anti-missile system, originally planned for Poland and the Czech Republic.
Many here expect the missile shield argument to be settled by the end of this year.
The START talks themselves, meanwhile, have proceeded cloaked in secrecy. Negotiators must agree on arcane and difficult issues, such as which weapons will be subject to cuts and what will be the rules for counting nuclear warheads.
A cut in nuclear arsenals would reduce costs as well as tensions.
For Russia, which spends about one tenth of what the U.S. spends on defense, an arms deal would maintain nuclear parity without the expense of replacing aging Soviet-era weapons.
"Practically all Soviet-built missiles will have to be written off over the next decade, and building replacements will be quite costly," said Alexander Pikayev, a top arms control expert at Russia's Institute for World Economy and International Relations.
On the other hand, some experts say, failure to ratify the deal could trigger a U.S.-Russia arms race.
"It's very important for both Medvedev and Obama to reach agreement," Pikayev said. "They won't be able to improve the U.S.-Russian relations without that deal."
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