ST PETERSBURG, Russia, May 26 (Reuters) - Russian President Vladimir Putin said goodbye to his friend George on Sunday after taking in the ballet, staying out past midnight on the canals, and, of course, signing a landmark arms control pact.
In all the years of superpower summitry, it is hard to remember two leaders having a more demonstrably fabulous time than Putin and U.S. President George W. Bush.
The ex-KGB spy and the Texas rancher talked about their kids, heaped praise on each other and perfected the timing of what has to be one of the oddest comedy acts in recent memory.
The lighthearted show has serious implications: if Russians were unsure whether Putin was sincere in his sudden recent westward foreign policy lurch, the round-the-clock televised camaraderie appeared intended to settle the case.
"I'm absolutely convinced that the future of this country is incredibly bright," Bush told students at Putin's alma mater, St Petersburg State University.
"First, because of the great imagination and intellect of the Russian people and secondly, because you've got a leader who understands that freedom is going to lift the future of this country."
But after a summit that was heavier on style than on substance, there will be serious work to do to ensure that the latest thaw does not end in a refreeze, as so many have before.
Differences, notably over Russian technology exports to Iran, which Washington calls the world's greatest nuclear proliferation threat, still lurk just below the surface.
"Russia is still on probation," said Pavel Felgenhauer, an independent defence analyst based in Moscow.
"They say: 'Yes, Putin is a nice guy, but there's lots of nasty guys in town around here'. And of course they're right. Russian foreign policy is erratic and not really decided yet."
TREATY BILLED AS COLD WAR'S END
The centrepiece of this week's summit was the Treaty of Moscow, billed as a landmark arms control pact that would finally bury the legacy of the Cold War, committing both countries to cut deployed long-range nuclear arsenals by two-thirds over the next decade.
Signing an arms pact was a minor victory for Putin: the Bush administration had long resisted putting its pledges on paper.
"I believe we have every reason to consider this visit a success," Putin told reporters after Bush left on Sunday. "The fact that we have reached agreements on these issues and even signed documents, I believe is tremendous progress."
He could also point to other victories. Bush notably avoided any reference to accusations of Russian atrocities in rebel Chechnya, a war Washington considers brutal but also sees as part of own struggle with Islamic militants.
The cordiality between Bush and Putin has perhaps been rivalled in the past only by the hearty, back-slapping relationship between their direct predecessors, Bill Clinton and Boris Yeltsin.
Unlike Clinton and Yeltsin, and a majority of other post-war presidential pairs, Bush and Putin have not had to overcome a wide difference in age or physical health.
But Friday's three-page treaty looks nothing like the arms reduction accords of the past, with their precise timetables for specific cuts and elaborate mechanisms for verification.
The treaty commits Russia to making nuclear cuts that economic reality would have surely imposed anyway. Washington can keep its warheads in storage and re-arm them at any time.
"President Bush said, basically: 'You have a good president, but we need thousands of warheads if something goes wrong with you guys'," Felgenhauer said.