World leaders have gathered in Berlin for a summit hosted by German Chancellor Angela Merkel and marking what is likely to be President Barack Obama's farewell visit to Europe.
Obama has joined leaders from Germany, Britain, France, Italy and Spain to discuss security and economic challenges as President-elect Donald Trump prepares to take office.
Since Obama's arrival on Wednesday on his sixth and last trip to Germany as president, he and Merkel have held several meetings focusing on issues of globalisation and trans-Atlantic cooperation.
The talks come largely in the context of what the election of Trump will mean to efforts to seek peace in Ukraine and Syria, the strength of the Nato alliance, trade agreements, efforts to fight climate change and other pressing issues.
At a news conference with Obama on Thursday, Merkel diplomatically said she was approaching the incoming Trump administration "with an open mind".
Although Brexit is not on the agenda, Theresa May is likely to discuss the situation with her European counterparts, including a one-to-one meeting with Merkel. The meeting follows a fresh warning from Berlin about the difficulties May will face as she attempts to secure a Brexit deal.
Trump has applauded the British decision to leave the EU and had meetings with Ukip leader Nigel Farage.
For his part, Obama said on Thursday his hope was that the Brexit negotiations be "conducted in a smooth and orderly and transparent fashion and preserve as closely as possible the economic and political and security relationships between the UK and EU".
Still, he noted that he considered the EU "one of the world's great political and economic achievements".
On other issues, Obama said he hoped for continuity in US-European relations under Trump, saying "how important it is that we work together".
He said that "continued global leadership on climate in addition to increasing private investment and clean energy is going to be critical".
After his meetings in Berlin, Obama will head to Peru for an Asian economic summit, on the final leg of his last foreign tour.