Vice President Joe Biden has sworn in Samantha Power as the new U.S. ambassador to the United Nations.
Biden posted a picture of Friday's White House ceremony on the social media site Twitter. The ceremony was a day after the Senate overwhelmingly approved Power by a vote of 87-10.
Power is a 42-year-old former journalist and National Security Council staff expert. She was described Thursday by Senate Foreign Relations Committee chairman Robert Menendez as "a tireless defender of human rights."
Power won one of journalism's highest awards, the 2003 Pulitzer Prize, for a book describing what she called timid U.S. responses to human rights crises, including massacres in Rwanda and Bosnia in the 1990s. She most recently called the U.N. failure to end widespread killing in Syria's civil war "a disgrace that history will judge harshly."
A White House statement Thursday called Power "a fierce advocate for universal rights" and one of America's leading foreign policy thinkers.
Power succeeds Susan Rice, now the president's national security advisor.