John Negroponte was sworn in as the U.S. deputy secretary of state at a ceremony held in the State Department chaired by Secretary of State Condoleezza Rice and attended by President George W. Bush.
"Mr. President, in John Negroponte, you could not have chosen a more capable, more dedicated, or more experienced public servant," Rice said at the ceremony.
"I am so delighted to welcome John back, because he will be a great leader and an inspiration to the men and women of American diplomacy," Rice said.
Bush nominated Negroponte in January to take the post, which has been vacant since Robert Zoellick left office in July last year.
Prior to this, Negroponte was the first Director of National Intelligence. Negroponte also held several high-profile posts in the Bush administration, including those of UN ambassador and ambassador to Iraq in the months leading up to the invasion of Iraq.
A career diplomat, he also served as ambassador to the Philippines, Mexico and Honduras, where he was accused of overseeing the arming of Nicaraguan rebels during the Iran-Contra affair of the 1980s.