Obama and Russian President Dmitry Medvedev are both in Seoul for the Nuclear Security Summit.
The two leaders held bilateral talks and Obama apparently was standing near a live microphone when he told Medvedev they would have to wait until after the election to resolve their differences concerning the European missile defense shield.
"This is my last election, and after my election I have more flexibility," Obama said.
The White House said Obama was just expressing political reality and noted the Russians have a presidential election coming up as well.
"I think President Obama said, for instance, in his speech today [Monday] very clearly that he is interested in pursuing additional reductions in nuclear stockpiles. We would very much like those discussions about future reductions to include tactical nuclear weapons and non-deployed nuclear weapons," Deputy National Security Adviser for Strategic Communications Ben Rhodes told reporters after the meeting. "Whenever we have that discussion with the Russians, they obviously want to talk about missile defense because they see it as related to strategic stability even though we don't."
Washington has said the missile defense shield would ensure safety for Europe in the event of an attack from Iran. Moscow has opposed the system, fearing it would be used against Russia and its interests.