German Chancellor Angela Merkel greets US President Barack Obama in Berlin on November 18, 2016
Berlin (AFP) - US President Barack Obama and top European leaders warned Donald Trump on Friday to stick to a strong transatlantic partnership, urging ongoing NATO cooperation and pressure against Russia.
Trump's shock election win has sparked fears of drastic policy upheavals as he has challenged a near 70-year-old security shield for US allies under NATO and vowed to withdraw from hard-fought deals on the climate and Iran's nuclear programme.
The US president-elect's admiration for Russian President Vladimir Putin has also raised questions over his attitude toward Moscow's backing for Syrian President Bashar al-Assad as well as Russia's role in the Ukraine conflict.
In the Berlin talks, Obama and the leaders of Britain, France, Germany, Italy and Spain "agreed on the necessity of working collectively to move the transatlantic agenda forward," said a White House statement.
That meant "securing diplomatic resolution to the conflicts in Syria and eastern Ukraine", including putting the heat on Russia through continued sanctions until it meets its commitments under a peace deal for Ukraine.
At the moment, progress on the ceasefire accord was "unseen," said German Chancellor Angela Merkel after the talks, in which the leaders also affirmed the "importance of continued cooperation through multilateral institutions, including NATO".
- Cautious optimism -
Obama had voiced cautious optimism that Trump could change his position and tone once he takes office in the White House in January.
"There's something about the solemn responsibilities of that office ... that forces you to focus, that demands seriousness," Obama said at a joint press conference with Merkel on Thursday.
NATO chief Jens Stoltenberg said Friday he had had a positive talk with Trump on the future of the US-led alliance.
"We both underlined the enduring importance of NATO and increased defence spending," Stoltenberg tweeted.
Obama told Spiegel magazine and public broadcaster ARD in remarks published Friday that he believed that "ultimately the president-elect will recognise" the value of maintaining a deal on curbing Iran's nuclear ambitions.
On climate change, which Trump has described as a "hoax", Obama said that even if his successor is "less interested in this issue than I am, I think that it can survive -- even if for the next two or three or four years, they are not as active as I was".
But Trump's election has already claimed an early casualty, a planned US-EU free trade deal which Merkel admitted could not be concluded now.
- Stand united -
Friday's meeting is the first of its format since the US vote and opened with the burning question of the US-led coalition's battle against Islamic State jihadists in Syria and Iraq.
But it also included an "emotional and affectionate" exchange as European leaders said goodbye to Obama, who was on his farewell tour of the continent, said an aide to French President Francois Hollande.
The US leader took pains to stress the importance of a united Europe, as the EU faces unprecedented challenges that threatened to rip it apart.
"The EU remains one of the world's great political and economic achievements, and those achievements should not be taken for granted," Obama said, as he urged the leaders not to lose sight of the 28-member bloc as a whole.
France's Hollande is grappling with record low approval ratings ahead of next May's election that could see far-right candidate Marine Le Pen reach the second round run-off vote, or even win outright.
Italy's Matteo Renzi and Spain's Mariano Rajoy meanwhile are battling state debt woes.
And British Prime Minister Theresa May, whose country shocked the world when it voted in June to quit the EU, said before talks with Merkel that her plans to launch Brexit negotiations were "on track".
Ahead of the potentially bitter Brexit negotiations, Obama called on Brussels and London to work towards future relations that "preserve as closely as possible the economic and political and security relationships between the UK and EU".
- 'She's tough' -
Obama's choice of Berlin as the main stop for his last official European tour has been interpreted by some as the passing of the baton of the defence of liberal democracy to Merkel, who also chairs the Group of 20 industrial and developing powers next year.
In a departure for the leader of a country that once took lessons from the United States on basic freedoms, Merkel's congratulatory message to Trump tied future cooperation to honouring common democratic values, including "respect for human dignity".
Obama gave a ringing endorsement to Merkel, who is expected to announce Sunday that she will run for a fourth term in next year's elections, and acknowledged that she would have heavy international burdens to shoulder.
"I wish I could be there to lighten her load somewhat. But she's tough," said Obama, who Friday headed off to Lima for a summit of Asia-Pacific leaders.