Russian and U.S. officials signed an important agreement on civilian nuclear power on Tuesday that will give the U.S. access to Russian technology and could hand Moscow lucrative deals for storing spent fuel. The deal, signed on the eve of Dmitry Medvedev's inauguration as President, signals a reversal in U.S. policy on cooperating with Russia on nuclear issues. Cooperation had cooled in recent years, mainly due to disagreements over how to handle the perceived nuclear threat from Iran. "The U.S. and Russia were once nuclear rivals,' U.S. Ambassador William Burns said after a signing ceremony. "Today, we are nuclear partners with unique capabilities and unique responsibilities for global nuclear leadership.' The deal