At the invitation of German Chancellor Angela Merkel, President Obama joined her on Thursday at an event in Berlin.

At the invitation of German Chancellor Angela Merkel, former President Obama joined her on Thursday at an event in Berlin organized by the Protestant church, reports Politico.
He spoke about global responsibility, education, and helping those in need. 
Obama, in an apparent reference to the views of the current U.S. president, said “If there are disruptions…if there is bad governance, if there is war or if there is poverty, in this new world that we live in we can’t isolate ourselves - we can’t hide behind a wall.”
He also commented, “If I become so convinced that ‘I’m always right,’ the logical conclusion of that often ends up being great cruelty and great violence.”
Obama is an incredibly popular international political figure in Germany, while his successor, President Trump, has struggled to gain the nation’s affection, notes the Huffington Post.
The wall Obama was likely referencing, the one Trump would like to build along the U.S.-Mexico border, has faced significant opposition so far. 
According to the New York Times, Trump backed "off a demand that the project be funded in a short-term spending measure" in late April to prevent a government shutdown.
Despite past troubles, wall money is included in Trump’s proposed budget for 2018, reports MarketWatch.
In a Tuesday presentation of the plan, White House Office of Management and Budget Director Mick Mulvaney said, “We are absolutely dead serious about the wall," and noted it remains among the president’s top priorities.