In addition to Joe_the_Lion's input, I think, as an American, that most of the threat of nuclear attack originates in the entirely unpredictable middle east (read Iran). Right now, central and even parts of northern and western Europe can be in striking distance of missiles launched from that area. It's not particularly Russia tha tposes the threat but they are certainly complicit in possibly being the source of nuclear warheads the Iranians are unquestionably seeking. Therefore, in this scenario, it's not the U.S. that's at risk, but Europe, and it's Europe that stands to benefit (as in years gone by) from the U.S.'s umbrella...
As mentioned on another thread, overlooked is the fact that Bush has consistently offered to Putin the opportunity to particiapte in the technology thereby allowing Russia to protect itself as well. Putin has declined. In my opinion his actions (Putin's) speak volumes about his intent to maintain relations with Iran, primarily to assure a continued supply of cheap oil, but also insuring Iran sees Russia as a needed ally...