Obama leaves Germany on Friday for Peru; he has meetings with Angela Merkel, Theresa May and other European leaders in the morning before his departure

There's nervousness about Trump's election after his criticism of NATO and


President Barack Obama says he is 'cautiously optimistic' about Donald Trump's presidency, but the president-elect needs to moderate his tone as he transitions from campaigning to governing and carefully negotiate with Russia.

'He ran an extraordinarily unconventional campaign and it resulted in the biggest political upset in perhaps modern political history,' Obama said of his successor at a Thursday press conference.

The president shed more light on their conversation a week ago in the Oval Office, saying today that he told Trump, 'What may work in generating enthusiasm or passion during elections may be different than what will work in terms of unifying the country and gaining the trust even of those who didn't support him.'

Obama says he came away from their meeting with the impression that the incoming president absorbed his message. He'll be looking to the president-elect's staffing decisions as a measuring stick, Obama added.

'My hope is that that's something that he is thinking about because not only is the President of the United States somebody that the entire country looks to for direction, but sets the agenda internationally in a lot of ways,' Obama said from Berlin.

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President Barack Obama says he advised Donald Trump to moderate his tone as he transitions from campaigning to governing and warned him today about negotiating with Russia

The world will be especially watchful of Trump's relations with Russia and its president, Vladimir Putin.

Obama said it is his hope that Trump takes a 'constructive approach' to working the military super power as he did, 'but the president-elect is also wiling to stand up to Russia where they are deviating from our values and international norms.'

'I don't expect that the president-elect will follow exactly our blueprint or our approach,' he said.

'But my hope is he does not simply take a realpolitik approach and suggest we cut some deals with Russia, even if it hurts people or violates international norms or leaves smaller countries vulnerable or creates long-term problems in region like Syria that we just do whatever is convenient at the time,' Obama warned the incoming executive.

Obama said he'll do everything he can from the Oval Office to help ensure a smooth transition for Trump, who will soon find out that 'even when you are attentive, there are so many things that come across your desk that people are going to question you, and you’re going to have opponents and you’re going to have critics.'

'There's something about the solemn responsibilities of that office, the extraordinary demands that are placed on the United States, not just by its own people, but by people around the world that forces you to focus,' he observed.

Obama shared part of his Oval Office conversation with Trump" 'What I said to him was that what may work in generating enthusiasm or passion during elections may be different than what will work in terms of unifying the country and gaining the trust even of those who didn't support him'

The position 'demands seriousness,' he said.

'And if you're not serious about the job, then you probably won't be there very long because it will expose problems,' Obama assessed.

He said Trump will find out 'fairly quickly' that he can't take his new role 'casually' and that he must listen and reach out to a variety of groups to get a favorable outcome.

That includes his detractors. The U.S. president would not call on Americans protesting Trump to quiet their demonstrations. 'One of the great things about our democracy is it expresses itself in all sorts of ways,' he said, 'and that includes people protesting.'

'I would not advise people who feel strongly or are concerned about some of the issues that have been raised during the course of the campaign, I wouldn't advise them to be silent,' Obama said at a news conference. 'What I would advise...is that elections matter, voting matters, organizing matters, being informed on the issues matter.'

DINNER FOR TWO: Merkel and Obama dined together last night at the Hotel Adlon in Berlin. Merkel noted today they have had 'difficulties' in their relationship but also 'very close cooperation'

Yet he scolded his own naysayers, including those in Germany, for looking past the lessons of the 20th century.

Young people in developed countries take for granted the peace and prosperity that has defined their lifetimes, he said at a joint presser with Chancellor Angela Merkel this afternoon. 'I do think that sometimes there's complacency,' he said.

'Democracy is weakened,' Obama argued, when 43 percent of the American electorate doesn't turn out to vote. 'If we are not serious about facts and what's true and what's not, and particularly in an age of social media....if we cant discriminate between serious arguments and propaganda, then we have problems.'

The outgoing world leader warned in the diatribe that 'democracy will break down' if 'people, whether they're conservative, liberal, left or right, are unwilling to compromise and engage in the democratic process and are taking absolutist views and demonizing opponents.'

Healthy democracies require continuous engagement, he said, that doesn't begin and end with one election.

'Here in Europe I think there are a lot of young people who forget the issues that were at stake in the Cold War, who forget what it meant to have a wall,' he said.

'And I'll be honest, there have been times when I have listened to the rhetoric in Europe, where an easy equivalence somehow between the United States and Russia and between how our governments operate, verus other governments those distinctions aren't made.

In a diatribe Obama also said that young people in developed countries take for granted the peace and prosperity that has defined their lifetimes, he said at a joint presser with Chancellor Angela Merkel this afternoon. 'I do think that sometimes there's complacency,' he said

The U.S. president would not, however, call on Americans protesting Trump to quiet their demonstrations. A Rutgers University student is seen protesting Trump today in New Brunswick, New Jersey

Incredulous, Obama said his government 'like any government...we have our flaws. We have operated imperfectly. There are times when we've made mistakes. There are times where I've made mistakes, or our administration hasn't always aligned ourselves with the values that we need to align ourselves with - it's a work of constant improvement.

'But I can say to the German people that the United States has been good for Germany, has looked out for Germany, has proved security for Germany, has helped rebuild Germany and unify Germany,' he asserted.

'I can say across Europe that many principles that have been taken granted here,' he said.

Obama cited free speech, civil liberties, independent judiciaries and anti-corruption task forces as examples. 'Those are principles that, not perfectly but generally we have tried to apply.'

'And that should be remembered,' he added, on a defiant note.

Obama called Merkel a 'great friend and ally' and said he 'could not ask for a steadier or more reliable partner on the world stage'

The sitting president, who often advises young people not to become cynical about politics, later said he is 'always optimistic' - he's had to be with a name like 'Barack Obama - and his positive outlook has been enhanced by the enormous change he's witnessed in the United States and around the world in his lifetime.

Obama returned to Berlin yesterday, the city where he first wowed the world with an iconic speech eight years ago.

He held the biggest rally of his 2008 campaign in the German capital, using the once-divided city's rebirth as a symbol of progress as he was greeted like a rock star by 200,000 awestruck supporters at the Victory Column monument at sunset.

In a speech that was in direct contrast to his brash successor, he made a hopeful call for a world without nuclear weapons and urged those present to tackle climate change saying 'this is the moment we must come together to save this planet'.

As Obama returned to Berlin on a gloomy November day, the jubilation of his last visit has been replaced by great uncertainty and unease about the future of the liberal global order.

President Obama visits Berlin today, in the backdrop of Brandenburg Gate, on the last leg of his final European tour

The trip was a marked contrast to the jubilation of his 2008 visit where he wowed the crowd as a senator

In 2008 Obama was greeted as a rock star in a unifying speech post the Bush era that lauded open and diverse societies

On the last leg of his farewell European tour as president, Obama aimed to ease fears about the future of the transatlantic partnership and thanked Merkel for her close friendship during his two terms.

'As I reflect back over the past eight years, I could not ask for a steadier or a more reliable partner on the world stage, often through some very challenging times,' he said Thursday.

Obama promised the German people he would be back again after he leaves office - 'I have somehow continued to miss Oktoberfest. So that's probably something that is better for me to do as a former president rather than as president. I'll have more fun.'

Merkel thanked him in turn for 'the friendship you’ve always demonstrated.'

'Thank you for the reliable friendship and partnership you demonstrated in very difficult hours of our relationship,' she said, hinting at the spying scandal that rocked US-German relations several years ago. 'This is the end of an eight-year cooperation that was very close, indeed,' she said in her opening remarks.

In a joint article to coincide with his arrival in Germany, Obama and Merkel appealed for ongoing cooperation on the basis of shared principles to fight climate change, ensure collective defense within NATO, and promote free trade - all issues which Trump has criticized.

'These values of democracy, justice and freedom form the foundation of our successful economies,' they wrote in business magazine Wirtschaftswoche.

'We owe it to our industries and our peoples - indeed, to the global community - to broaden and deepen our cooperation,' they said, in an indirect attack on the 'America First' rhetoric favored by Trump.

Obama reiterated at their press conference Trump's comments to him last week about NATO.

'I am encouraged by the President-elect’s insistence that NATO is a commitment that does not change. And his full commitment to NATO as the foundation for our international security I think is very important,' Obama said.

The talks come against a backdrop of European nervousness about the election of Donald Trump as Obama's successor in the White House following his criticism of NATO and scepticism about climate change

After Trump's victory on November 8, Merkel - the leader of Europe's top economic power - expressed a desire to maintain close ties with Washington.

But in her message of congratulations, Merkel pointedly said cooperation between the two countries must be based on shared democratic principles and 'respect for human dignity'.

She said Thursday that she has been impressed with the transfer of power from one political party to the next thus far and said, 'I approach this with an open mind, and I’ll do it on the basis of a deep conviction with President-elect Donald Trump.'

Obama and Merkel were photographed having dinner by candlelight on Wednesday night after the United States president's arrival. The pictures were released Thursday by the German government.

In an interview with German public broadcaster ARD and news magazine Der Spiegel, Obama said Merkel had served her country well in the 11 turbulent years she has been in power.

'She has great credibility and she is willing to fight for her values,' he said on his sixth trip to Germany as president. 'I am glad that she is there. I think the German people should appreciate her. Certainly I have appreciated her as a partner.'

Obama and Merkel appealed for ongoing cooperation on the basis of shared principles to fight climate change, ensure collective defence within NATO, and promote free trade

Obama has relied on Merkel's strength in Europe on several fronts including helping to defuse the Ukraine conflict and taking in hundreds of thousands of Syrian refugees

The president praised Merkel as someone 'who is willing to fight for her values' and said 'the Germans should appreciate her'

Obama and Merkel emphasised the trans-Atlantic friendship has helped forge a climate accord, provide help for refugees worldwide, form a collective defence under Nato, and strengthen the global fight against the ISIS

Merkel and Obama have enjoyed a close relationship, and he seems to be counting on the German leader's strength to help counter the brash and isolationist tone voiced by president-elect Mr Trump during the election campaign

Obama broke with tradition and said he would be inclined to vote for Merkel if he were a German citizen - and she chooses to run again.

'Although we have not always been in sync on every issue,' he said. 'I think she's been outstanding.'

'So it's up to her whether she wants to stand again, and then ultimately it will be up to the German people to decide what the future holds.'

Adding, 'If I were here, and I were German, and I had a vote, I might support her.' To laughter he said, 'I don't know whether that hurts or helps.'

Tomorrow Obama will meet with Merkel again before he departs, as well as President Francois Hollande of France, Prime Minister Mariano Rajoy of Spain, Prime Minister Matteo Renzi of Italy, and Prime Minister Therese May of the United Kingdom.

He'll leave at 12:30 pm local time for Lima, Peru.

Obama's visit to Germany was a marked contrast to his 2008 trip when, as a young senator, he thrilled a crowd of 200,000 in a speech that lauded open and diverse societies.

In a reference to the Berlin wall, he said: 'The walls between races and tribes, natives and immigrants, Christian and Muslim and Jew cannot stand. These now are the walls we must tear down.'

Germans at the Victory Column today said they were disappointed to see him depart and worried about what the Trump administration would bring.

'We were so hopeful after George W. Bush left office,' said Thomas Schmidt, 54, a business clerk who recalled being 'thrilled' when he watched Obama's Berlin speech on television.

'It was a euphoric mood, a little bit like when the Berlin Wall fell. The feeling now with Trump is much more wary. No one knows what he might do.'

Matthias Krah, 43, an IT project manager, found the prospect of Trump in the White House 'scary' and predicted a major realignment of transatlantic ties.

He said: 'It means we Europeans will need to look inward. Maybe we can start doing without the US.'

Obama greets Merkel this afternoon in what is his last trip to Europe as he prepares to handover the presidency to Trump

Obama and Merkel have forged a strong partnership over the years, even surviving the revelation American spies had listened to her mobile phone calls