There was a significant shift some time during the first term of the Bush the Lesser presidency. I remember a summit early on when Putin and Bush appeared to be the best of buddies, but within a couple of years it appeared the US had not been dealing in good faith and Puting got pissed off and hardened Russia's position.

A society committed to the notion that government is always bad will have bad government. And it doesn't have to be that way. — Paul Krugman