A senior adviser to U.S. President Barack Obama said that Russia has some reasonable concerns about U.S. missile defense plans, according to AP. Russia has strongly opposed U.S. missile defense plans in Europe. Moscow says the system could undermine the deterrent of its vast nuclear arsenal. The Bush administration dismissed those concerns. It said that the system was aimed at countering Iran and that its capabilities were too limited to pose a threat to Moscow. However, Obama's coordinator for weapons of mass destruction policy, Gary Samore, said Friday that Russia's objections are legitimate as Washington and Moscow pursue nuclear reductions. He said, «when we go down to really low numbers then missile defense has a potential capability.»