US Supreme Court Chief Justice John Roberts (2nd from R) administers the oath of office to US President Barack Obama (L) as first lady Michelle Obama (C) and daughters Malia and Sasha (R) look on during ceremonies on the West front of the US Capitol in Washington, January 21, 2013. [Photo/Agencies]

WASHINGTON - US President Barack Obama on Monday took oath for his second term in the public inauguration ceremony at the Capitol grounds, reaffirming America's founding principles in a call for unity and promising to try and uphold peace in the world.

Obama made the calls in his inaugural address. He said the founding values of America have never been "self-executing," calling on the nation to "bridge the meaning of those words with the realities of our time."

"We have always understood that when times change, so must we," said Obama. "A decade of war is now ending. An economic recovery has begun."

Mapping out his foreign policy for the next four years, Obama said "we, the people, still believe that enduring security and lasting peace do not require perpetual war...We will show the courage to try and resolve our differences with other nations peacefully  not because we are naive about the dangers we face, but because engagement can more durably lift suspicion and fear."

He also assured allies that the United States will "remain the anchor of strong alliances in every corner of the globe," while promising the country "will respond to the threat of climate change, knowing that the failure to do so would betray our children and future generations."

The president will participate in a parade and two inaugural balls later in the day.