US Vice President JD Vance launched a withering attack Friday against European policies on immigration, populist parties and free speech, echoing the views of President Donald Trump, whom he called Washington's "new sheriff in town".
Vance also stressed Europe must "step up" in managing its own security, a key bone of contention.
His speech was a combative broadside at the Munich Security Conference at a time of deep transatlantic discord over defence, trade and other issues,
"There is a new sheriff in town under Donald Trump's leadership," said Vance.
"We may disagree with your views, but we will fight to defend your right to offer it in the public square. Agree or disagree."
Vance also charged that "across Europe, free speech, I fear, is in retreat", echoing Trump's attacks on online "censorship".
Vance urged European countries, including host country Germany, which faces elections on February 23, to "change course" on immigration.
His speech came a day after a 24-year-old Afghan man was arrested in Munich over a car-ramming attack that wounded 36 people.
"How many times must we suffer these appalling setbacks before we change course and take our shared civilisation in a new direction?" he said.
"Why did this happen in the first place? It's a terrible story but it's one we've heard way too many times in Europe and unfortunately too many times in the United states as well.
"An asylum seeker, often a young man in his mid-20s already known to police, rams a car into a crowd and shatters a community."
Defending political parties that oppose immigration and their supporters, he added: "No voter on this continent went to the ballot box to open the floodgates to millions of unvetted immigrants."
Germany warned earlier Friday against foreign "meddling" in its politics after Vance called for a bigger role for Europe's anti-immigration parties, nine days before the German general election.
Vance told the Wall Street Journal: "Unfortunately, the will of voters has been ignored by a lot of our European friends" on the issue and urged governments not to exclude anti-immigration parties.
Germany has suffered several high-profile attacks blamed on asylum seekers and migrants, prompting the far-right Alternative for Germany (AfD) to further intensify its anti-migrant campaigns.
German government spokesman Steffen Hebestreit said outsiders should not be "meddling in the internal affairs of a friendly country".
They "may not have a full overview of the political debate" in Germany, he said.
The far-right AfD looks set for its best ever result of around 20 percent in the election on February 23, current polling suggests.
The party has received enthusiastic backing from Elon Musk, the world's richest man and a key Trump ally.
Vance said that Germany should get used to the Tesla and SpaceX boss weighing in, just as the United States tolerated criticism by Swedish climate activist Greta Thunberg.
"If American democracy can survive 10 years of Greta Thunberg's scolding, you guys can survive a few months of Elon Musk," he said.
"But what German democracy, what no democracy -- American, German or European -- will survive is telling millions of voters that their thoughts and concerns, their aspirations, their pleas for relief are invalid or unworthy."
Vance also touched on a heated German pre-election debate around the need for mainstream political parties to maintain a so called "firewall" of non-cooperation with the AfD.
"Democracy rests on the sacred principle that the voice of the people matters," he said. "There's no room for firewalls."
