Russian diplomats expelled from U.S. arrive in Moscow The Russian diplomats who were expelled from the U.S. arrived back in Moscow on Sunday. The latest diplomatic breakdown was triggered after Britain and its allies sought to punish the Kremlin after determining it was "highly likely" Moscow was behind the chemical agent attack of Russian double agent Sergei Skripal and his daughter Yulia in Salisbury, England. CBS News foreign correspondent Charlie D'Agata reports.