Another woman has been sworn in as the U.S. ambassador to the United Nations, but she is no diplomat.

Samantha Power took the oath of office in a private ceremony in Vice President Joe Biden's West Wing office, a building where Power had worked as a National Security Council aide to President Obama.

The Irish-born adviser was actually a Pulitzer Prize winning journalist and scholar on genocide issues whose book "A Problem from Hell: America and the Age of Genocide" was honored a decade ago.

Power was a senior foreign policy adviser to the 2008 Obama campaign and made headlines when she called his then-rival Hillary Clinton a "monster," but she now joins the ranks of women who have held top foreign policy positions in the administration: Secretary of State Clinton, and Susan Rice, who recently left the UN post to become the White House National Security Advisor.

@AnnCompton