 The Obama administration has done everything in its power to destroy the atmosphere of trust which could have encouraged cooperation Russian President Vladimir Putin on Monday suspended a treaty with Washington on cleaning up weapons-grade plutonium, signaling he is willing to use nuclear disarmament as a new bargaining chip in disputes with the United States over Ukraine and Syria.Starting in the last years of the Cold War, Russia and the United States signed a series of accords to reduce the size of their nuclear arsenals, agreements that have so far survived intact despite a souring of U.S.-Russian relations under Putin.But on Monday, Putin issued a decree suspending an agreement, concluded in 2000, which bound the two sides to dispose of surplus plutonium originally intended for use in nuclear weapons.The Kremlin said it was taking that action in response to unfriendly acts by Washington. It made the announcement shortly before Washington said it was suspending talks with Russia on trying to end the violence in Syria.The plutonium accord is not the cornerstone of post-Cold War U.S.-Russia disarmament, and the practical implications from the suspension will be limited. But the suspension, and the linkage to disagreements on other issues, carries powerful symbolism.Read more: Reuters