(From the nytimes.com) Politics, diplomats like to say, stops at the water’s edge. But this week, the politics of the presidential election crashed into a nuclear security summit half a world away. On Tuesday, President Obama declared that the United States and Russia could not realistically work out their dispute over an American missile defense system this year because politics during the presidential campaign would make it impossible to win support for any compromise.

“The only way I get this stuff done is if I’m consulting with the Pentagon, if I’m consulting with Congress, if I’ve got bipartisan support,” Mr. Obama said to reporters here. “Frankly, the current environment is not conducive to those kinds of thoughtful consultations.”

The tempest began on Monday, when Mr. Obama was caught by a microphone in a moment of candor, telling President Dmitri A. Medvedev of Russia that he would have more flexibility to deal with the thorny issue of missile defense after the election in November.

Read more here: Nuclear Conference in Korea Collides with U.S. Election