British PM Cameron pays official visit to U.S. U.S. President Barack Obama (R) meets with British Prime Minister David Cameron in the Oval...

British PM Cameron pays official visit to U.S.

U.S. President Barack Obama (R) meets with British Prime Minister David Cameron in the Oval Office of the White House in Washington D.C., capital of the United States, March 14, 2012. (Xinhua/Zhang Jun)

U.S. President Barack Obama (1st, R) and British Prime Minister David Cameron (2nd, R) wave to the crowd with their wives during an official ceremony at the White House in Washington D.C., capital of the United States, March 14, 2012. (Xinhua/Zhang Jun)

U.S. President Barack Obama (L) and British Prime Minister David Cameron (R) attend an official ceremony at the White House in Washington D.C., capital of the United States, March 14, 2012. (Xinhua/Zhang Jun)

U.S. President Barack Obama and British Prime Minister David Cameron attend an official ceremony at the White House in Washington D.C., capital of the United States, March 14, 2012. (Xinhua/Zhang Jun)

.S. President Barack Obama (R) and British Prime Minister David Cameron (L) attend an official ceremony at the White House in Washington D.C., capital of the United States, March 14, 2012. (Xinhua/Zhang Jun)

U.S. President Barack Obama (L) and British Prime Minister David Cameron (R) attend an official ceremony at the White House in Washington D.C., capital of the United States, March 14, 2012. (Xinhua/Fan Zhe)

U.S. President Barack Obama (R) meets with British Prime Minister David Cameron in the Oval Office of the White House in Washington D.C., capital of the United States, March 14, 2012. (Xinhua/Zhang Jun)

U.S. President Barack Obama meets with British Prime Minister David Cameron in Washington D.C., capital of the United States, March 14, 2012.