"No Kings" demonstrators took to the streets in New York, Los Angeles, Chicago, Philadelphia, Houston, Atlanta and hundreds of other cities across the United States to condemn what they call Trump's dictatorial overreach.

Trump's huge military parade will see tanks rumble through Washington for the first time in decades to mark the 250th birthday of the US Army -- and the president's own.

"I think it's disgusting," protester Sarah Hargrave, 42, told AFP at a protest in the Washington suburb of Bethesda, describing Trump's parade as a "display of authoritarianism."

Republican Trump, who has begun his second term by pushing presidential powers to unprecedented levels, boasted on his Truth Social network that it was a "big day for America!!!"

He added that Russian strongman Vladimir Putin, for whom he has repeatedly expressed admiration, had "very nicely" called him to wish him a happy birthday.

The two leaders also agreed on the need for an end to the Iran-Israel conflict -- a war in which US forces are aiding Israel to shoot down Tehran's missiles.

Both the conflict and the targeted shootings of two lawmakers in Minnesota cast a shadow over the grand spectacle in the US capital.

Trump was quick to condemn the attacks outside Minneapolis in which former state speaker Melissa Hortman died along with her husband, while the other lawmaker and his wife have been hospitalized with gunshot wounds.

- Political violence -

The murders were the latest in a string of incidents of political violence, including an attempt on Trump's life in July last year.

Officials were looking for Vance Boelter, 57, in connection with the Minnesota incident. "No Kings" flyers and a manifesto that named numerous officials were found in the car of the suspect, who impersonated a policeman, authorities said.

Organizers cancelled "No Kings" protests in the state, but said they expected millions of people to take part in 1,500 cities in the rest of the country.

Some protesters targeted Trump's Mar-a-Lago estate in Palm Beach, Florida -- while a small group even gathered in Paris.

Thousands turned out in Los Angeles to protest Trump's deployment of troops in America's second-largest city following clashes sparked by immigration raids.

Trump has promised to use "very big force" if protesters attempt to disrupt the army parade in Washington.

But disruption could also come from thunderstorms forecast to hit Washington.

Trump put on a brave face, saying on Truth Social: "Our great military parade is on, rain or shine. Remember, a rainy day parade brings good luck. I'll see you all in DC."

- $45 million -

The military parade is the biggest in Washington since the end of the Gulf War in 1991 and has led to accusations by Trump's opponents that he is behaving like a king.

The procession will feature 7,000 troops, more than 50 helicopters and dozens of armored vehicles including giant Abrams tanks, with the display estimated to cost of up to $45 million.

Soldiers will wear uniforms dating back through US history to its independence from Britain as they march past landmarks including the Washington Monument to end up at the White House.

The parade is meant to end with the army's Golden Knights parachute team dropping in to present Trump with a US flag -- on Flag Day, which marks the adoption of the Stars and Stripes.

Trump has been obsessed with having a parade since his first term as president when he attended France's annual Bastille Day parade in Paris at the invitation of President Emmanuel Macron.

Critics have accused Trump of acting like autocrats in Moscow or Pyongyang.

California's Governor Gavin Newsom, who slammed Trump for sending National Guard troops into Los Angeles without his consent, called it a "vulgar display of weakness."