"In this new world we live in, we can’t isolate ourselves. We can’t hide behind walls," the former president said in Berlin. | AP Photo How Obama not so subtly undercuts Trump Obama’s calculated but opaque opposition to Trump was on full display in Berlin.

When they realized former President Barack Obama was going to be in Berlin the same day President Donald Trump was going to be in Brussels, Angela Merkel was the one who called the White House to break the news.

The German chancellor invited Obama to the event in front of the Brandenburg Gate last year, before the election. Officially part of a multi-day gathering sponsored by the Protestant church in Germany, focused on youth and highlighting an exchange program between Berlin and Chicago, it was really about letting Obama boost his friend ahead of her fall reelection campaign and begin the international phase of his own post-presidency.


But, as soon as he accepted earlier this year, it also became an integral piece of Obama’s approach to Trump: present the contrast by continuing to pop up, push back on the sense that Trump’s winning while barely saying a word explicitly about Trump.

The only request the former president’s aides made of the organizers of the Berlin event was it not be structured as an Obama versus Trump debate. Other than that, they said, “the conversation can go where it will.”

"In this new world we live in, we can’t isolate ourselves. We can’t hide behind a wall," Obama said Thursday, in the closest he came to directly taking on his successor.

Obama is aware how much people are searching for Trump attacks in every word he says. He’s just as opposed to Trump’s presidency as he was on the morning of Election Day. How he’s doing this is deliberate.

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"Obama has a clear view on how countries, including the U.S., should confront the challenges we all face. He didn't shy away from making that case as president and he's not going to now,” said one person close to him. “But not everything needs to be said to be understood — as Woody Allen famously put it, 80 percent is just showing up."

With his early post-presidency focused on inspiring more young people to get involved civically, he said Thursday of the kind of burn-down-the-establishment that propelled Trump, those who believe “politicians are all corrupt, and institutions are all corrupt … if that’s your attitude, then yes, things will get worse. But it’ll get worse because you did not make the commitment to live out the values and the things you believe in most.”

Obama talked health care and immigration policy. He defended his cautious use of drones in response to a question from a German college student. He urged against militarism and the kind of bigger military budget that Trump has touted — “the national security budget shouldn’t just be seen as military hardware, it should be seen as development, it should be seen as diplomacy,” he said.

While Trump was meeting with European leaders, Obama was cautioning against absolutism and self-assurance.

“If I become so convinced that, ‘I’m always right,’” Obama said, “the logical conclusion of that often ends up being great cruelty and great violence.”

Berlin was Obama’s last foreign stop as president last November, as part of a trip the week after the election that was meant to be a warm send-off, but after Trump won, became a tough tour trying to explain to a startled Europe and the world what had happened and why he still believed he’d be proven right over time. As he did nonstop in those days after the election, on Thursday, he was back to quoting Martin Luther King Jr.’s “the arc of the moral universe is long, but it bends toward justice.”

But Merkel, who was open about rooting for Hillary Clinton and now has been trying to manage a relationship with a president who bashed her on the campaign trail and famously didn’t shake her hand during her Oval Office visit, will live out the strange balance on Thursday: she had breakfast in Berlin with the former president before the event, and flies to Brussels to have dinner with Trump as part of the NATO summit.

David Axelrod, Obama’s former top adviser and a person who attended both Obama’s post-presidency debut at the University of Chicago in April and his speech at the John F. Kennedy Library earlier this month in which he called on Republicans to have the “political courage” to keep Obamacare in place, said the difference between Obama and Trump is so clear in politics, demeanor and appearance that the former president doesn’t need to do much to keep alive the sense of clear alternative.

“President Obama is acutely aware of the parameters of his role but also the power of the platform,” Axelrod said. “He's not going to be the point of the spear in the political wars.”

But that doesn’t mean at all that Obama’s off the battlefield. After all, sitting in the audience in Berlin was Obama’s former deputy national security adviser Ben Rhodes, who’s still on the Obama payroll and is extremely close to the former president, and has become one of Trump’s most frequent and harsh critics through Twitter.

“When he sits down with Angela Merkel in Berlin to discuss the importance of civic engagement and democratic participation, the spirit of the event and warmth of their relationship will strike an unmistakable contrast,” Axelrod said. “Sometimes a picture is worth a thousand words.”

In America, many Democrats are desperate for Obama to be doing more against Trump, but he’s refusing to both out of a sense that he shouldn’t be so explicitly political as a former president and out of conviction that the more he speaks, the fewer new leaders will rise up. In Germany, he remains immensely popular — the crowd in front of the Brandenburg Gate was a sliver of the 200,000 who showed up to see him in 2008, but they were rapt, some holding signs like, “Welcome Home,” “You’re Looking Great,” and “Du Bist Ein Berliner.”

Trump is not popular in Germany and much of Europe at all.

Merkel was clearly happy to have Obama there, using him as both a buffer and explainer for some the issues she’s taken the most heat for, like welcoming tens of thousands of refugees. Smiling and bantering throughout, she even seemed to tease the cynical jokes that with Trump’s election, she’s now the leader of the free world: when the moderator directed a question toward Obama as “the most powerful man for a while sits next to me,” she interrupted, “I’m sitting next to you, not the president,” according to a simultaneous translation provided by the event.

White House press secretary Sean Spicer did not respond to questions about Obama’s comments, or Obama’s decision to do the event at all in the middle of Trump’s first international trip as president.

Beyond the basic deference of not engaging Trump directly, Obama isn’t going to let the current president define or limit what he does.

“When we found out he was going to be in Europe,” said one Obama Foundation aide, “it didn’t have any impact on what we were doing.”

“We’re not going to step into his space, but we have our own agenda,” the aide added.

At the same time Obama was onstage with Merkel, Trump was meeting with European Council Presidents Donald Tusk and Jean-Claude Juncker, who’ve been critical of Brexit and the Trump worldview.

"Do you know, Mr. President, we have two presidents in the EU?" Tusk said as they posed for photographers who were briefly allowed into the meeting.

"I know that,” Trump replied.

"One too much,” Juncker chimed in.

