US authorities provided no national crowd estimate.It is the third time in less than a year that Americans have taken to the streets as part of a grassroots movement called No Kings, the most vocal and visual conduit for opposition to Trump since he began his second term in January 2025.In New York, America's most populous city, tens of thousands of demonstrators rallied, including Oscar-winning actor Robert De Niro, a frequent Trump critic, who called the president "an existential threat to our freedoms and security".Protests unfolded from Atlanta to San Diego, with Alaskans joining the mix later in the day."No country can govern without the consent of the people," 36-year-old military veteran Marc McCaughey told Agence France-Presse in Atlanta, where thousands turned out."We're out here because we feel that the Constitution is under threat in a multitude of different ways So it's a terrible situation we're in," 67-year-old retiree Robert Pavosevich told AFP.Trump himself was in Florida for the weekend.The anti-Trump mood has spilled beyond US borders, with rallies on Sunday AEDT in European cities including Amsterdam, Madrid and Rome, where 20,000 people marched under a heavy police presence.The first No Kings nationwide protest day came last June on Trump's 79th birthday and coincided with a military parade he organised in Washington