World leaders met in Washington Tuesday on the second-day of a nuclear summit aimed at reducing weapons stockpiles.
US President Barack Obama wants the other 46 countries attending to agree cutting their nuclear arsenal and securing remaining stockpiles to keep them out of the hands of extremist groups.
He achieved a major coup Monday night when Ukraine offered to give up its enriched uranium stocks by 2012.
Two states, however, were conspicuous by their absence: Iran and North Korea had not been invited.
Washington suspects both of trying to build a nuclear bomb.