WILL NUCLEAR COOPERATION BE A CASUALTY OF THE UKRAINE CRISIS?

-- Russia's brazen takeover of the Crimean Peninsula and the inherent disregard for an international agreement Moscow signed, vowing to respect Ukraine's borders in exchange for the smaller nation's abandonment of nuclear weapons, have Western world leaders worried that the superpower could just as easily disregard the nuclear nonproliferation pacts that marked the now-distant U.S.-Russia diplomatic "reset." President Obama: We need "Russia to move back those troops" Mr. Obama and U.N. Secretary-General Ban Ki-moon had appealed repeatedly to Russian President Vladimir Putin to refrain from annexing Crimea - with little success. The U.S. and the European Union have imposed sanctions on Russian banks and individuals, while the U.N. General Assembly voted Thursday to support Ukraine's new government and call the referendum that resulted in the annexation illegal. The Security Council is now working to get more observers into Ukraine and Crimea to guard against attacks on civilians.