Who stated anything inregards to the missile shield differences between Russia and the U.S, we are talking cooperation inregards to the war on terror, joint intel shared between Russia and the U.S is of great benefit to both countries to disrupt terrorist networking and attacks.Also in ur dream to see US and Russian work together, especially when come to "Missile Sheild Programme" located in Poland (Missile Launcher System) and Czech Republic (Radar & EWC System).
Also if I may add that Russia may of not had a terror attack at the same magnitude as of 911 the smaller ones like the school and theater attacks were horrible for the Russian people and to the people worldwide, you can bet most certain that Russia will do whatever it takes to ensure that another one will not occur on Russian soil and interests abroad, including working with the U.S or anyone else for that matter, the stakes are way to high.