Nearly four years after Presidents George Bush and Vladimir Putin formed warm personal ties, relations between Moscow and Washington are again chilly, and testing the partnership.
Thursday's much-awaited summit in Slovakia could redefine US-Russian ties, as two different worldviews contribute to rising tensions over the spread of democracy, a potentially nuclear Iran, and missile sales to Syria.
The rekindled US focus on democracy - after three years of seeing nearly every foreign policy issue through the prism of the war on terror - has deepened anxiety for Russia leading up to the summit.
Bush's comments Monday in Brussels that the US and Europe "should place democratic reform at the heart of their dialogue with Russia" underscores how at odds the two leaders are over the importance of democratic reforms.
Although both nations remain committed to strategic issues of nuclear nonproliferation and the war on terror, the Kremlin has deepened its authoritarian rule, opposed the US invasion of Iraq, and accused Washington of trying to lure former Soviet states into the Western camp, by helping orchestrate revolutions in Ukraine and Georgia.
"From the Russian perspective, this is all a double standard," says Fiona Hill, a Russia expert at the Brookings Institution in Washington. "There is certainly this widespread anti-Americanism within the Russian elite, a feeling that the US lost any moral high ground it could possibly have because of Iraq, Abu Ghraib, and increasing concern of US intentions locally."
Including all these issues in a single summit meeting may not be easy, but some argue that it's to Putin's advantage to meet face to face with Bush.
"In many ways, this summit is an attempt by Putin to come back to his core strength," says Pavel Baev, a Russia analyst at the International Peace Research Institute in Oslo, Norway. "He feels that his real effort is that man-to-man, eye-to-eye relationship ... and probably feels he can reconnect to President Bush."
There may be one trump card up his sleeve, too, that has become more important since the Jan. 30 election in Iraq. A decision to send Russian troops to Iraq - or just the promise of such troops, serving as peacekeepers as part of the US-led coalition - would be a seen as a commitment to the new Iraqi government, and not the continuing US occupation.
Since the Iraqi vote, US officials may have already sent the message to Moscow, Mr. Baev says, that Russian troops would be "greatly appreciated."
"[Putin] would be very reluctant to play that card, and would use it only as a last resort, but still he might," says Baev.
Russia has reaffirmed its commitment to Iranian nuclear power - despite Washington's concern that Iran's efforts mask a nuclear weapons program - and is reportedly in talks to build more nuclear power plants. Just two days after Thursday's Bush-Putin summit, Iran and Russia are to sign a long-delayed deal on nuclear fuel supply. Bush has called Iran part of an "axis of evil," whereas Putin last week said he was "convinced" Iran had no intention of building atomic bombs, and called Iran a "long-standing partner."
Another issue Bush and Putin may discuss is Syria. Moscow confirmed last week that it had struck a deal with Syria, which Washington accuses of sponsoring terrorism, to sell anti-aircraft missile systems.
The latest rhetorical flare-up came over Ukraine's "Orange Revolution," which resulted from the rigged election between Kremlin-backed Viktor Yanukovich and Western-leaning Viktor Yushchenko. Putin even went to Kiev to campaign for Mr. Yanukovich before the November election.
After a revote, opposition candidate Mr. Yushchenko - who has made no secret of his wish to bring Ukraine firmly into European institutions - took power. That result delivered a blow to the Kremlin, which was beginning to reexert influence in the former Soviet space, to counter Europe's own expansion of the EU and NATO alliance.
"A lot of [Russia's] strategy was built on the assumption that Ukraine was the place where we will show our strength ... it will be a contest, that we are confident we can win," says Baev. "Now Ukraine is gone, you are left with such a huge yawning hole in the middle of your strategy, that it's not about how to close it - you need to abandon the strategy, and think about something new." he says.
The recent cold spell in relations has been driven by growing criticism in Washington and Europe of Putin's efforts to erase Democratic norms in Russia. US Secretary of State Condoleezza Rice - a Soviet specialist before joining the government - reportedly told Russian Foreign Minister Sergei Lavrov earlier this month that such steps "do make it more difficult to pursue full and deep relations."
Russian officials have tried to put a favorable spin on events, and the US-Russia "partnership" that they say will be enhanced during the summit in Bratislava.
"We are now debating whose democratic system is better and whose human rights are more correct," Mr. Lavrov told Russia's Channel One television last week. "I do not fear that such debates will overshadow the essence of Russian-US relations."
Still, Russia has been taken aback by the outcome in Ukraine, because of what it says about the Kremlin's worldview. "Russia is out of step now with all its neighbors," says Hill. "It's easy to cast this off as a Western plot by the US and Europe trying to wrest juicy morsels away from Russia. But the sad fact is that Russia itself isn't moving forward in any way anymore."
Part of the problem, she says, is an economy that has surged in growth in recent years, off the back of high oil prices. "So much cash is sloshing about, there is no imperative to be innovative and take drastic action, [so] the whole momentum is slowing and growth is tapering off," says Hill. "And out of this malaise, you get a sense of crisis, because you've got foreign policy failures, and these failures in domestic policy. It's just got everyone rattled."