Ukrainian President in attendnace: Russia's Putin did not make the trip
World leaders are in Washington for the Nuclear Security Summit at the White House.
With less than 10 months left in office, U.S. President Obama is convening heads of government from more than 50 countries in a final foreign policy push.
Among those in attendance is Ukrainian President Petro Poroshenko. Ties between Kyiv and Washington have deepened since the Kremlin began its military aggression in eastern Ukraine two years ago.
Meanwhile, America's ties with Russia have plummeted to lows not seen since the Cold War. Russian President Putin is not attending the nuclear summit.