President Trump said it was “about time” America celebrated its military victories as a mass parade to mark the US army’s 250th anniversary was held against a backdrop of nationwide protests.

Washington was locked down and the capital’s airspace closed to flights as 6,500 troops marched down Constitution Avenue and helicopters flew overhead, fulfilling Trump’s long-standing ambition to stage a military parade — the first held in the American capital for more than 30 years.

The celebrations came just hours after a Democratic politician and her husband were shot dead in their Minnesota home by a man believed to be impersonating a police officer. Threats against other politicians in Texas were made on a day of widespread unrest and protests against the Trump administration, timed to coincide with Saturday’s $46 million event.

Speaking after the hour-long parade along Constitution Avenue, Trump praised America’s soldiers for their service in major conflicts — from the Revolutionary War to the Second World War and the Gulf War — and suggested the US should follow other countries in staging military celebrations.Protests took place in Los Angeles on the day of the paradeSPENCER PLATT/GETTY IMAGESDemonstrators carried a giant inflatable balloon depicting the presidentDAVID MCNEW/GETTY IMAGES“Every other country celebrates their victories. It’s about time America did too,” he said. “That’s what we’re doing tonight. And watching this magnificent display, our souls are filled with gratitude for every generation of warriors who have worn the uniform all the way back to the very beginning.”In his remarks Trump also appeared to reference the assassination attempt he survived in Pennsylvania last summer when, after being shot in the ear, he shouted to the rally crowds: “Fight, fight, fight.”• The parade in picturesOn Saturday evening the president said: “Time and again, America’s enemies have learnt that if you threaten the American people, our soldiers are coming for you. Your defeat will be certain. Your demise will be final and your downfall will be total and complete. Because our soldiers never give up, never surrender and never ever quit. They fight, fight, fight and they win, win, win.”The parade featured infantry units and military equipment which have been used in every major war in which the US army has fought, including Second World War-era tanks, Apache helicopters deployed to Iraq and lightweight artillery.Trump watched the proceedings from an elevated viewing stand behind bulletproof glass. He was joined by the first lady Melania Trump and several members of his cabinet, including vice-president JD Vance and Pete Hegseth, the secretary of defence.Organisers for Saturday’s parade said they were expecting “hundreds of thousands” to attend but images of empty seats in stands along the parade route suggested turnout may not have been as high as hoped. It is possible the poor weather kept many at home.Crowds were sparse in places as the rain dampened proceedings in WashingtonREUTERS/CARLOS BARRIAThousands more took to the streets of America’s biggest cities to protest the parade. Demonstrations were held in more than 2,000 cities and towns, organised by the “No Kings” movement — a coalition of organisations calling for a “nationwide day of defiance”.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 a federal building that had been a focus of much of the demonstrations.The president and first lady watch on from a viewing stand surrounded with bulletproof glassANDREW HARNIK/GETTY IMAGESCrowds observe as military helicopters whizz pastREUTERS/EVELYN HOCKSTEINAuthorities in Texas also warned of “credible threats” that were made against political figures planning to attend protests in Austin. An alert was sent out by the state’s Department of Public Safety on Saturday afternoon — just hours after the Minnesota shootings.House Speaker Emerita Melissa Hortman, 55, a Democrat, and her husband were killed in Brooklyn Park. The state senator John Hoffman, 60, also a Democrat, and his wife were targeted in their home in nearby Champlin in a related shooting. They survived and have since undergone surgery.A manhunt is under way for the suspect Vance Boelter, 57, who was said to have impersonated a police officer.