Czech Republic ? President Bush’s attempts to soothe rising tensions with Russian President Vladimir Putin will be tested today when the two leaders come together for the first time since a U.S. proposal to place a missile defense system in Eastern Europe brought a new low to post-Cold War relations between their two countries.

Bush, speaking Tuesday on the eve of a summit of the G-8 major industrial nations in Germany, tried to reassure Putin that rogue nations like Iran, not Russia, are the true target of the missiles, just two days after the Russian president threatened to re-aim part of his country’s arsenal at Europe in retaliation for the U.S. missile plan.

“The Cold War is over. It ended,” Bush said at an appearance in the Czech Republic, where the U.S. hopes to install radar for the missiles. “My message will be, ‘Vladimir – I call him Vladimir – that you shouldn’t fear a missile defense system. As a matter of fact, why don’t you cooperate with us on a missile defense system?'”

The appeal to Putin came as observers in Moscow say the missile issue has contributed to a Cold War-like mind-set taking hold in the Kremlin – a mentality in which Moscow sizes up the U.S. as a nemesis instead of a partner.

While analysts say Putin’s tough reaction to the missile plan also may be an effort to bolster his domestic political standing and split the U.S. and Europe over the issue, the Kremlin’s angst about the West has been fueled by the perception that the missile defense system upsets the strategic balance between the world’s two largest nuclear arsenals.