President Donald Trump's long-sought military parade rolled though the streets of downtown Washington on Saturday, but the celebration of the US Army's 250th anniversary was marred by a day of violence and discord.

In the hours before the parade began, hundreds of thousands of Americans marched and rallied in streets in cities from New York to Chicago to Los Angeles, protesting Trump's actions while in office, in the largest such actions since his return to power in January.

Earlier in the day, a gunman assassinated a Democratic lawmaker and wounded another in Minnesota and remained at large.

Meanwhile, Israel on Saturday pounded Iran with a second barrage of strikes in a bid to destroy its nuclear program after Iran retaliated with strikes the evening before, stoking fears of a mushrooming conflict between the two nations.

All of it followed a week of tension in Los Angeles, where protests over federal immigration raids resulted in Trump calling in National Guard troops and US Marines to help keep the peace, over the objections of the state's Democratic Governor Gavin Newsom.

The parade, which falls on Trump's 79th birthday, kicked off earlier than expected with thunderstorms forecast in the Washington area.

Tanks, armored personnel carriers and artillery rumbled down the parade route along storied Constitution Avenue, an unusual sight in the US where such displays of military are rare.

"Every other country celebrates their victories, it's about time America did too," Trump told the crowd following the parade.

Thousands of spectators lined up along the route. Trump watched the proceedings from an elevated viewing stand behind bulletproof glass.

Some of the president's opponents also managed to find a spot along the parade route, holding signs in protest. Other demonstrators were kept separate from the parade crowd by local police.

The US Army has brought nearly 7,000 troops into Washington, along with 150 vehicles, including more than 25 M1 Abrams tanks, 28 Stryker armored vehicles, four Paladin self-propelled artillery vehicles, and artillery pieces including the M777 and M119.

ARMY'S HISTORY

The parade traced the history of the Army from its founding during the Revolutionary War through modern day. Trump frequently stood and saluted troops as they marched by.

Members of Trump's cabinet including Pentagon chief Pete Hegseth and Secretary of State Marco Rubio looked on.

Trump had first expressed interest in a military parade in Washington early in his first 2017-2021 term in office.

In 1991, tanks and thousands of troops paraded through Washington to celebrate the ousting of Iraqi President Saddam Hussein's forces from Kuwait in the Gulf War.

The celebrations were expected to cost the US Army between $25 million and $45 million, US officials have told Reuters. That includes the parade itself as well as the cost of moving equipment and housing and feeding the troops.

Critics have called the parade an authoritarian display of power that is wasteful, especially given Trump has said he wants to slash costs throughout the federal government.

Bryan Henrie, a Trump supporter, flew in from Texas to celebrate the Army's anniversary and did not see any issues with tanks rolling down the streets of Washington.

"I don't see a controversy. I will celebrate safety and stability any day over anarchy," 61-year-old Henrie said.

'SHAME! SHAME!'

Earlier in the day, thousands marched in Washington and in other cities in protest of Trump's policies. The demonstrations were largely peaceful, and marked the largest outpouring of opposition to Trump's presidency since he returned to power in January.

In Los Angeles, however, police, some on horseback, used flash-bang grenades and tear gas to push back a crowd of protesters around the federal building that has been a focus of much of the demonstrations.

Earlier, the crowd had yelled at the Marines guarding the facility, "Shame! Shame!" and "Marines, get out of LA!"

Anti-Trump groups planned nearly 2,000 demonstrations across the country to coincide with the parade. Many took place under the theme "No Kings," asserting that no individual is above the law.

Thousands of people of all ages turned out in and around Bryant Park in Midtown Manhattan, many carrying homemade signs that played off the "No Kings" theme. "No crown for a clown," said one. Actor Mark Ruffalo was among the demonstrators, wearing a hat that read "immigrant."

"We're seeing dehumanizing language towards LGBT people, towards people with autism, towards people with other disabilities, racial minorities, undocumented people," said Cooper Smith, 20, from upstate New York. "Somebody's got to show that most Americans are against this."

Protesters in downtown Chicago stood off against police on Saturday, with some waving upside-down American flags and chanting: "Who do you protect? Who do you serve?" and "No justice, no peace."

Members of the far-right Proud Boys, ardent Trump supporters, appeared at an Atlanta "No Kings" protest, wearing the group's distinctive black and yellow colors.

About 400 protesters, organized by a group called RefuseFascism.org, marched through Washington and gathered for a rally in a park opposite the White House. Trump had warned people against protesting at the parade itself, saying that "they're going to be met with very big force."

Sunsara Taylor, a founder of RefuseFascism, told the crowd, "Today we refuse to accept Donald Trump unleashing the military against the people of this country and in the streets of this country. We say, 'hell no.'"

Bd-Pratidin English/ARK