Germany’s president has said his country has overcome its postwar reluctance to participate in world affairs and is prepared to assume a more active role politically and militarily in the wake of the Brexit referendum and the election of Donald Trump.

Joachim Gauck said many Germans were increasingly accepting of their country’s responsibility to assert itself internationally, despite their awareness of the suspicions some still hold regarding any form of German dominance.

“We can be proud that this Germany is different from the other Germanies of history, that we live in lasting peace alongside our neighbours, and are a reliable partner within the EU and Nato; that our country is robustly at peace with itself and enjoys a welfare state which stops people falling into destitution,” he said.

“Notwithstanding that some Germans still find it difficult to stomach the idea of Germany assuming greater responsibility internationally … I think it’s right we should shoulder that responsibility. A country which trusts itself is a more reliable partner for everyone.”

Gauck, 77, was speaking to the Guardian and four other major European newspapers, shortly before retiring this month from Germany’s highest office.

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He said the postwar stance of many Germans, so haunted by their militaristic past that for decades some utterly rejected the idea of the country even having its own army, had gradually given way to a more pragmatic approach.

“Even increasing the defence budget is no longer met with resistance from the majority of the population,” he said. “For a while some Germans were almost ashamed of having an army at all.”

But, he explained, the more Germans accepted “that their homeland has become a reliable country that boosts legal certainty, sound institutions and a stable democratic citizenry, the readier they will be to bring those achievements to bear and assume more responsibility on the international stage”.

A former Protestant pastor who rose to prominence as an anti-communist civil rights activist in East Germany, Gauck said he was confident that precisely because of the lessons it had learned through bitter experience, the Germany he knew would “weather very well” the political developments, including Eurosceptism and neo-nationalism, that had gained ground during the five years he had been in office.

“I think we would be the last in Europe to feel tempted to go back to any kind of authoritarian model of society,” he said. Having endured excessive nationalism most Germans for years had wanted never to be nationalist again, he said. “First we had national socialism, then, in parts of Germany, communism with its promise of salvation and its political alienation and crimes. These experiences left their mark on us.”

Gauck confidently maintained that despite the growing number of “critical questions” Germans, like other EU members, had about the club, they would “staunchly stand by the European project” because “Europe is in Germany’s DNA”.

Gauck said he heard the clear message sent out by the Brexit referendum result, namely the “need to slow down” with the project. Both that and Trump’s election, he said, had underlined the need for politicians to learn to speak a simpler language and to not leave “sections of the population who felt they had been left behind” to the populists.

“It is becoming clear … how urgently we need to talk to the more sceptical and less politically involved section of the electorate,” he said. “If enlightened politics is to succeed, it will need to speak a language that is not just understood by the elite, that does not shy away from expressing simple and emotional things. We must not leave straightforward speech to the populists and the fearmongers.”

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He believed that it was in part what he called “directionless pride” that had led to the Brexit result.

“A great nation’s pride in its wonderful traditions and in what used to be a very comprehensive global sphere of influence, for many people in Britain … seems to have nowhere to go these days,” he said. While the political, business and media elite had “managed to keep that directionless pride on a leash for a long time” he believed it was the referendum that had finally set it loose.

“I also believe Britain will undergo a period of intense reflection about this decision over the next 10 or 15 years,” he added.

Gauck, who before he became president had been keeper of the archives of the East German secret police, the Stasi, noted that the current nostalgia in Britain for what he called the days when it was a nation with “a large sphere of influence” was a stark reminder to him of “something I noticed in eastern Germany 20 years ago”.

“The people had wanted to throw off communism, but then a few years later they started to grow nostalgic for it,” he said. The phenomenon is often described as “ostalgia”, or longing for East Germany.

He predicted that individual countries were “too weak” to go it alone outside the EU, and that recognising that, other EU members were unlikely to follow Britain’s example.

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Gauck admitted Chancellor Angela Merkel’s “open door” policy, which had seen well over a million immigrants arrive in Germany, had deeply divided sections of the German populace, but he refused to say it had been a “miscalculation”. A “culture of welcome”, he said, had grown out of what he called “decent Germans” wanting to show they were different to those who carried out arson attacks on refugee accommodation. “They wanted to show that’s not who we are,” he said.

“It is of course very easy to say, as some do, that Europe wouldn’t have a refugee problem if it wasn’t for Angela Merkel. But the thing is, refugees exist, with or without Merkel, and all of us in Europe need to deal with that. We all bear a joint responsibility.”

Gauck called for improved security of Europe’s external borders with better regulated access and “legal access routes for people who are either in need of protection or who are needed in Europe”, particularly in the light of terrorist attacks on the continent.

He condemned the recent decision by Trump to ban the nationals of several Muslim-majority countries from entering the US, calling it “incompatible with our concept of human dignity, equality and religious freedom”.

He added: “The disappointing thing is that these are concepts we Europeans actually share with the Americans. It was [they] who upheld those values during the darkest times in Europe’s history and returned [them] to our continent.”

On a deeply personal note, he said that for decades of his life he had only been able to relate to his own country “in a totally negative way. It was not our spiritual homeland. Many Germans despised their own country.”

It had taken the reunification of Germany in 1990 and the political and economic stability that slowly emerged over the following years for him to even begin to consider it with any sense of pride.

“It wasn’t until after I became president that I first used the word ‘pride’ in relation to my country,” he said. “I was over 70 at that point. That’s how long it took me to do what any 16 year old in other countries is able to do.”