ssia and the U.S. after the two former Cold War adversaries recently signed a nuclear reduction treaty.</p>

<p>Obama also recently declared his Russian counterpart, Dmitri Medvedev, would help the U.S. "secure strong, tough sanctions on Iran."</p>

<p>But Moscow announced Friday it will start loading fuel into Iran's first and only nuclear power plant next Saturday, giving Tehran a boost as it struggles with international sanctions and highlighting differences between Moscow and Washington over pressuring 