Over the last decade, Russia and the West have repeatedly clashed over security, trade and diplomatic issues. Take a look at the most critical moments.
The icy divide outlived the Cold War
1997-99 NATO Enlargement:
NATO invites Poland, the Czech Republic and Hungary to join the alliance. Russia protests, but the three countries join in March 1999.
NATO bombs Serbia to stop the war in the breakaway province of Kosovo. Russia protests, but is unable to intervene.
Russia invades its breakaway province of Chechnya. Western leaders accuse Russia of human-rights abuses, to the fury of its new president, Vladimir Putin.
Russia has opposed NATO's eastward expansions
2002-04 NATO and EU Enlargements:
NATO and the EU invite several new members from the former Soviet sphere to join. Russia again objects, but the enlargements take place in spring 2004.
2005-07 Trade Rows:
Following the EU's 2004 enlargement, new members Poland and Lithuania find themselves in conflict with Russia over a ban on Polish meat imports and a shut-off of oil to Lithuania. Both countries veto talks on a strategic EU-Russia deal. Moscow accuses them of holding its relationship with the EU for ransom.
2007 Missile Defense:
The US announces plans to site parts of an anti-missile system in NATO and EU members Poland and the Czech Republic. Russia threatens to aim nuclear missiles at the duo in response.
2007 Cyber War:
The Estonian government relocates a Red Army war memorial in Tallinn. Ethnic Russians retaliate by rioting in Tallinn, attacking EU diplomats in Moscow and launching a massive cyber-attack on Estonian government systems. European politicians condemn the attacks. Russia retorts by accusing Europe of trying to "rewrite the history" of World War II.
Kosovo declares independence in February. The US and most European states recognize it, but stress that it is a unique case. Russia condemns the move and warns that it will be seen as a precedent in other conflict areas such as Georgia.
2008 NATO Enlargement:
At a summit in April, NATO leaders agree that Georgia and Ukraine should join the alliance at an unspecified future point. Russia warns that this would destabilize the security situation in the Caucasus.