Barack Obama has arrived in Greece on the first stop of his final foreign tour as U.S. president.
Obama held talks with President Prokopis Pavlopoulos and Prime Minister Alexis Tsipra.
On November 16, he is scheduled to give a speech about democracy and globalization before flying on to Berlin.
More than 5,000 police were deployed in the streets of Athens for the two-day visit, while major roads were closed and public gatherings were banned in central areas of the capital.
Left-wing and anarchist groups have planned protest demonstrations during Obama's visit to Greece, the first by a sitting U.S. president since Bill Clinton in 1999.
Clinton's trip was marked with extensive violent demonstrations.
From Germany, Obama will travel to Peru for a summit of the Asia-Pacific Economic Cooperation forum before returning to Washington on November 19.
Obama's tour is expected to be dominated by concerns about President-elect Donald Trump.
On November 14, Obama sought to assure U.S. allies that Trump will honor the country's international alliances when he takes office in January.