Europe can no longer "completely depend" on the US and UK following the election of President Trump and Brexit, German Chancellor Angela Merkel says.
Mrs Merkel said she wanted friendly relations with both countries as well as Russia but Europeans had to "take their destiny into their own hands".
Her comments come after Mr Trump refused to re-commit to the 2015 Paris climate deal at the G7 summit.
Mrs Merkel is on the campaign trail ahead of elections in September.
"The times in which we could completely depend on others are on the way out. I've experienced that in the last few days," Mrs Merkel told a crowd at an election rally in Munich, southern Germany.
The relationship between Berlin and new French President Emmanuel Macron had to be a priority, Mrs Merkel said, adding: "We Europeans have to take our destiny into our own hands."
On Saturday, the German leader had described climate change talks at the G7 group of rich nations as "very unsatisfactory".
Leaders from the UK, Canada, France, Germany, Italy and Japan had re-affirmed their support for the Paris accord - but Mr Trump said he would make a decision in the coming week.
Mr Trump has previously pledged to abandon the Paris deal, and expressed doubts about climate change.
Speaking in Brussels last week, Mr Trump also told Nato members to spend more money on defence and did not re-state his administration's commitment to Nato's mutual security guarantees.
Mrs Merkel's latest comments are partly a move to appeal to German voters first and foremost, the BBC's Europe editor Katya Adler says.
Polls suggest Mrs Merkel is on course to be re-elected for a fourth term as German chancellor at elections in September.
Passionate Merkel - BBC's Damien McGuinness in Berlin:
It might have been thanks to the beer, pretzels and Bavarian brass-band enlivening the crowd.
But Mrs Merkel's words were uncharacteristically passionate and unusually forthright. By all means keep friendly relations with Trump's America and Brexit Britain, was the message - but we can't rely on them.
Rapturous applause greeted her fiery calls for Europeans to fight for their own destiny.
No wonder she's sounding confident. France has a new president who shares her pro free-trade, Europhile values, so there is a positive feeling in Europe that the EU's Franco-German motor is back in business.
With four months to go before elections, Angela Merkel's position also looks stronger than ever domestically. Initial enthusiasm for her centre-left rival Martin Schulz has fizzled out. And Sunday's beer-tent event underscored her strength by marking an end to a potential split with her Bavarian sister conservative party.
She might not have welcomed Brexit or Trump. But it seems that Mrs Merkel has decided that standing up for the EU will only strengthen her chances of winning another term in September.