US, Russian presidents met quietly at the Lisbon summit

ABOARD AIR FORCE ONE - United States President Barack Obama and his Russian counterpart Dmitry Medvedev held an unplanned meeting on the sidelines of a NATO summit in Lisbon in an effort to build confidence between the two nations, a White House official announced.

"They were able to go aside into a room by themselves and talk for 15 to 20 minutes," White House spokesman Ben Rhodes told reporters aboard Air Force One before it landed in Washington late on Saturday. "It was informal, it wasn't planned."

Only a translator accompanied the two leaders at their impromptu summit, US officials said.