Before the parade celebrating the Army’s 250th anniversary commenced, demonstrators filled streets and parks nationwide to condemn the Republican president as a dictator or aspiring monarch.

They criticized Trump for leveraging the military against protests concerning his deportation efforts and for deploying tanks, numerous marching troops, and military aircraft for a spectacle in the US capital.

In Washington, anti-war protesters unfurled signs that said “Homes not drones” not far from a display of armoured vehicles, helicopters and military-grade equipment on the National Mall set up to commemorate the Army’s birthday. Vendors outside the festival sold gear marking the military milestone. Others hawked Trump-themed merchandise.

Trump has been wanting a military parade in Washington ever since he watched one in France in 2017 and his dream is set to be finally realised on a day that coincides with his 79th birthday.

Doug Haynes, a Navy veteran who voted for Trump, attended the daylong festival to celebrate the Army’s 250th birthday, but said that the parade scheduled for later “was a little over the top”.

Pointing at a nearby tank, Haynes said that having them roll down the street was a “very bold statement to the world, perhaps”.

The military procession was set to step off from the Lincoln Memorial later Saturday, under the threat of stormy weather and to the accompaniment of protests elsewhere in the city.

Trump brushed off the possibility of both disruptions, with a social media post that said the “great military parade” would be on “rain or shine”.

The protests, he said earlier, would be “met with very big force”. Hours ahead of the parade, crowds of protesters with anti-Trump signs marched toward the White House, escorted by police vehicles and officers on bicycles. Some held a giant banner that read: “TRUMP MUST GO NOW.”

The parade was added just a few weeks ago to the planned celebration of the army’s birthday and has drawn criticism for its price tag of up to $US45 million ($69 million) and the possibility that the lumbering tanks could tear up city streets. The army has taken a variety of steps to protect the streets, including laying metal plates along the route.

About six in 10 Americans said the parade was “not a good use” of government money. The vast majority of people, 78 per cent, said they neither approve nor disapprove of the parade overall, according to a poll from The Associated Press-NORC Center for Public Affairs Research.

The daylong display of America’s army comes as Trump has shown his willingness to use the nation’s military might in ways other US presidents have typically avoided, inviting an array of lawsuits and accusations that he is politicising the military.

In the past week, he has activated the California National Guard without the governor’s permission and dispatched the US Marines to provide security during Los Angeles protests related to immigration raids, prompting a state lawsuit to stop the deployments.

He similarly sought to project military strength during his first presidential term, saying in 2020 that he wanted forces to “dominate” the streets following racial justice protests that turned violent and warning governors that he was prepared to send in active-duty fighters if they did not call out the National Guard in their states.

Earlier this week, Trump raised eyebrows during a speech at Fort Bragg when members of the 82nd Airborne Division, who were directed to stand behind Trump, booed and cheered during his incendiary remarks, including condemnation of his predecessor, Joe Biden. There also was a pop-up “Make America Great Again” merchandise stand nearby selling souvenirs to troops in uniform.

The Defence Department has a doctrine that prohibits troops from participating in political activity while in uniform. Members of Congress and military leaders have expressed concerns about the political displays during the speech at Fort Bragg.

Saturday’s pageantry was designed to fulfill Trump’s expressed desire for a big parade that he tried to get done in his first term after seeing one in Paris on Bastille Day in 2017. Trump said after watching the two-hour procession along the famed Champs-Élysées that he wanted an even grander one in Washington.

Saturday’s event is expected to include about 6600 soldiers, 50 helicopters and 60-ton M1 Abrams battle tanks, as well as possibly 200,000 attendees and heightened security to match.

The parade will wind down Constitution Avenue, lined with security fencing and barriers. Army helicopters and aircraft will fly above, and the march will be capped off by a parachute jump, a concert featuring “God Bless the USA” singer Lee Greenwood and fireworks.

It remained unclear whether any protests would disrupt the parade, though several hundred demonstrators assembled in the hours before. Officials have said they had no indication of any security threat.

“No Kings” rallies — organisers picked the name to support democracy and speak out against what they call the authoritarian actions of the Trump administration — unfolding in hundreds of cities — were meant to counter what organisers say are Trump’s plans to feed his ego on his 79th birthday and Flag Day.

Ahead of a rally and march toward the White House on Saturday afternoon, about 200 protesters assembled in north-west Washington’s Logan Circle and handed out signs and danced to upbeat music from a local street band, including “This Land Is Your Land.”

The mood was celebratory as the group chanted “Trump must go now” before erupting in cheers.

A larger-than-life puppet of Trump was wheeled through the crowd, a caricature of the president wearing a crown and sitting on a golden toilet.

Other protesters waved pride flags and hoisted signs, some with pointed messages such as “I prefer crushed ICE,” referring to the Immigration and Customs Enforcement agency. Other messages were: “The invasion was HERE Jan. 6th, NOT in L.A.” and “Flip me off if you’re a FASCIST.”

With rain expected, there was a chance the parade could be interrupted by thunderstorms.

The Army expects as many as 200,000 people could attend the festival and parade.

The parade is set to begin at 8.30 Sunday Australian time, but parts of it — including the horse-drawn caissons and other units — start at the Pentagon, head over a bridge and meet up with some of the heavier tanks and equipment. Officials did not want the more-than-60-ton M1A1 Abrams tanks and Stryker vehicles crossing the bridge.

Timed down to the minute, the march will be divided into sections by history — with equipment and troops in full dress from each period.

At the end of the parade, Trump will swear in 250 new or reenlisting troops, and the Army’s Golden Knights parachute team will jump onto the Mall. That will be followed by a concert and fireworks.