John Kerry is the new U.S. secretary of state, replacing former first lady Hillary Clinton as America's top diplomat.
Secretary John Kerry was sworn in at a private ceremony Friday, taking an oath administered by U.S. Supreme Court Justice Elena Kagan. He replaces his former Senate colleague, Hillary Clinton, who stepped down Friday after four years and visiting 112 countries as President Barack Obama's first-term secretary of state.
Clinton received a rousing send-off from diplomatic staff at the State Department's C Street entrance.
"Just standing here looking out at all of you, the people I have been honored to serve and lead and work with over the last four years is an incredible experience," she said.
Clinton says she is proud of the work done to elevate diplomacy and development and to understand the challenges and threats facing the United States.
"I know that the world we are trying to help bring into being in the 21st century will have many difficult days. But I am more optimistic today than I was when I stood here four years ago because I have seen day after day the many contributions that our diplomats and development experts are making," she said.
State Department employees welcome Hillary Clinton to the State Department building in Washington, January 22, 2009.
Former President Bill Clinton and daughter Chelsea during the ceremonial swearing-in for Hillary Clinton, February 2, 2009, at the State Department in Washington.
Clinton is accompanied by Turkish talk show hosts during the taping of a show for the Turkish news channel NTV in Ankara, Turkey, March 7, 2009.
President Obama and Clinton tour the Sultan Hassan Mosque in Cairo, June 4, 2009.
Hillary Clinton greets students upon arrival at the flood-stricken Malanday National High School at Marikina city, Philippines, November 12, 2009.
Clinton poses with U.S. Army soldiers during a brief visit to the U.S. camp at the military airport in Kabul, Afghanistan, November 19, 2009. Clinton visited to attend the inauguration of President Hamid Karzai.
Secretaryn Clinton and first lady Michelle Obama share a laugh during their participation in the 2010 International Women of Courage Awards at the State Department in Washington, March 10, 2010.
House Speaker Nancy Pelosi with Clinton in Statuary Hall on Capitol Hill in Washington, March 25, 2010, during the Women's History Month celebration. EPA Administrator Lisa Jackson applauds at left.
Afghan President Hamid Karzai, Clinton, and other foreign ministers pose for a group photo after the Kabul International Conference at the Foreign Ministry in Kabul, Afghanistan, July 20, 2010.
Clinton pauses to put on lipstick while talking with Turkey's President Abdullah Gul (R) at the start of a United Nations Security Council meeting at the U.N. headquarters in New York, September 23, 2010.
President Barack Obama and Secretary Clinton walk together off stage at a holiday reception for diplomats at the State Department in Washington, December 13, 2010.
Clinton checks her PDA upon her departure in a military C-17 plane from Malta bound for Tripoli, Libya October 18, 2011.
Clinton tours the Shwedegon Pagoda, a Buddhist temple founded between the 6th and 10th centuries AD, in Rangoon, Burma, December 1, 2011.
Pro-democracy leader Aung San Suu Kyi with Clinton after a meeting at Suu Kyi's residence in Rangoon, Burma, December 2, 2011.
Clinton walks with Bulgaria's Prime Minister Boiko Borisov (R) and members of his cabinet before a news conference in Sofia, February 5, 2012.
Clinton is pictured in the U.S. delegation as President Barack Obama meets with Mexico's President Felipe Calderon in Los Cabos June 18, 2012, to attend the G20 leaders summit.
Secretary Clinton embraces Triza Lapani after the teen helped Clinton put on a chitenje cloth, a traditional skirt, after speaking at Camp GLOW (Girls Leading Our World) run by the Peace Corps, in Lilongwe, Malawi, August 5, 2012.
Clinton is dressed by Emmie Phiri, chairperson of the dairy farmers during her visit to Malawi, August 5, 2012.
Clinton meets with Nelson Mandela, former president of South Africa, at his home in Qunu, South Africa, August 6, 2012. During his 94th birthday celebration in July, the leader met Hillary's husband and former U.S. President Bill Clinton.
Clinton adjusts her black pearl necklace, a gift from Cook Islands' Prime Minister Henry Puna (L) during a sustainable development and conservation event in Rarotonga, August 31, 2012.
Secretary Clinton at a news conference at the Great Hall of the People in Beijing September 5, 2012.
Actress Meryl Streep uses her iPhone to get a photo of her and Clinton following the State Department Dinner for the Kennedy Center Honors gala December 1, 2012 at the State Department in Washington.
Clinton holds up a football helmet with the State Department logo on it, presented by Deputy Secretary Thomas Nide, who joked that "Washington is a contact sport," January 7, 2013.
Outgoing Secretary of State Hillary Clinton testifies on Capitol Hill, January 23, 2013, before the Senate Foreign Relations Committee hearing on the deadly September attack on the U.S. diplomatic mission in Benghazi, Libya.
When Kerry starts work Monday, Clinton says she expects State Department staff will have the same focus and dedication they have shown her over the last four years.
Kerry is the 68th U.S. secretary of state since George Washington named Thomas Jefferson to the post in 1789.