Even at the height of the cold war, the shouting match between East and West was seldom cranked up to its current level.
Speaking to reporters in advance of Wednesday's Group of Eight (G-8) summit in Germany, Russian President Vladimir Putin on Saturday slammed the US for triggering "a looming arms race" with its plan to install antimissile interceptors in Central and Eastern Europe and warned that Russia might aim a fresh generation of nuclear missiles at "new targets in Europe." Last week, Mr. Putin seemed to echo former Soviet leader Leonid Brezhnev when he hailed a successful Russian ballistic-missile test as a response to American "imperialism."
Some of Washington's recent rhetoric has been similarly rancorous. State Department official David Kramer last week drew up a list of alleged Kremlin offenses, including "suppression of genuine opposition, abridgement of the right to protest, constriction of civil society, and the decline of media freedom."
Behind the chilly exchanges, many experts say, is a growing belief that the West miscalculated nine years ago by inviting Russia to join the G-8, which is widely viewed as the inner sanctum for the leading shapers of global economic policy and political direction.
"It was expected that admitting Russia to the G-8 ... would induce Russia to be a helpful, responsible participant in world affairs," explains Sir Nicholas Bayne, a British former diplomat who is now with the London School of Economics.
Putin's early years bore that out, he says. But now, "Putin's political activities are not nearly as responsible as we'd hoped. Russia doesn't fit into the way the G-8 is operated.... When you move into an issue like international energy, where Russia is a key player, things get very tense, because Russia will advance its agenda at the expense of others."
Chancellor Angela Merkel of Germany, which currently holds the rotating G-8 presidency, has indicated that she will strive to keep the summit's agenda focused on global warming and aid to Africa when the leaders of the US, Britain, France, Italy, Japan, Canada, and Russia join her in the Baltic Sea resort of Heiligendamm.
But experts say current tensions could come roaring to center stage over missile defense, Kosovo, Russian energy policy, the murder of Kremlin critic Alexander Litvinenko, or other issues from a growing list of East-West irritants.
"We're coming to this G-8 meeting in a very unpleasant atmosphere," says Pavel Mansurov, an editor at the independent Security Index journal in Moscow. "Relations are cooling fast, and problems are proliferating in many areas. It's going to be difficult for Putin."
As he prepared to embark for Europe, President George Bush seemed anxious to tone things down. "My personal message to Vladimir Putin is, there's no need to try to revive the cold war. It's over," he said.
But complicating the outlook is growing uncertainty over who will succeed Putin when his second term expires early next year.
Three G-8 leaders who enjoyed tight relations with Putin – former Italian prime minister Silvio Berlusconi, German ex-chancellor Gerhard Schröder, and former French president Jacques Chirac – are gone, and their successors are cooler toward Russia. And this will be the last G-8 summit for a leader who staunchly favored rapprochement with Russia, Britain's Tony Blair. Moscow's ties with London have soured since the fatal poisoning of Kremlin critic Alexander Litvinenko, followed by Britain's denied request to extradite ex-KGB agent Andrei Lugovoi from Russia and charge him with the crime.
Another potential spoiler is Kosovo, the mainly Albanian-populated Serbian province wrested away by NATO in a 1999 war. The Western consensus is that Kosovo should be helped along the path to independence, but Russia, a traditional ally of Serbia, has warned that independence for Kosovo could lead to a wave of breakouts by secessionist statelets around the former Soviet Union and beyond. "Russia has a different position on this, which the West just does not understand," says Alexei Makarkin, deputy director of the Center for Political Technologies, an independent Moscow think tank.
On Monday, Ms. Merkel said the issue is likely to be aired at Heiligendamm. "We must determine ... how much latitude still exists," she told Der Spiegel. "I believe time is of the essence here. We must make a decision soon."
Putin has also reacted coldly to Western criticisms of his human rights record, which he and Merkel publicly tussled over at last month's Russia-European Union meeting.
"The United States today is the main violator of freedoms and human rights on a global scale," he charged Saturday. "There are also grievances toward France, Great Britain, and Germany."
Experts say the East-West balance on a common energy policy, opening Russia to foreign investment, and a joint approach to Iran's nuclear ambitions, looks as vexed as ever. Some say friendly disagreement may be Heiligendamm's best outcome. "There is no doubt that there is a crisis in Russia's relationship with other G-8 countries," says Olivier Giscard D'Estaing, a former member of the French parliament. But, he says, there is no substitute for dialogue. "We need to keep Russia engaged."
• Mariah Blake contributed to this story from Hamburg, Germany.