A military parade commemorating the Army's 250th anniversary on Saturday

AP Washington

The grand military parade that President Donald Trump had been wanting for years barrelled down Constitution Avenue on Saturday with tanks, troops and a 21-gun salute, playing out against a counterpoint of protests around the country by those who decried the US leader as a dictator and would-be king.

The Republican president, on his 79th birthday, sat on a special viewing stand south of the White House to watch the display of American military might, which began early and moved swiftly as light rain fell and clouds shrouded the Washington Monument. 

The procession, with more than 6,000 soldiers and 128 Army tanks, was one Trump tried to make happen in his first term after seeing such an event in Paris in 2017, but the plans never came together until the parade was added to an event recognizing the Army's 250th anniversary. 

As armoured vehicles rolled down the street in front of the president, on the other side of the country, the Marines who Trump deployed to Los Angeles appeared at a demonstration for the first time, standing guard outside a federal building. Dozens of Marines stood shoulder to shoulder in full combat gear beside the National Guard, Homeland Security officers and other law enforcement. Hundreds of protesters facing them jeered in English and Spanish, telling the troops to go home.

A previously calm demonstration in downtown Los Angeles turned chaotic when police on horseback charged at the crowd, striking some with rods and batons as they cleared the street in front of the federal building and fired tear gas and crowd control projectiles. In Washington, hundreds carried signs with messages that included "Where's the due process?" and "No to Trump's fascist military parade" as they marched toward the White House. 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.