, June 14 -- Cities across the United States are gearing up for widespread protests on Saturday opposing President Donald Trump, as authorities call for calm, National Guard units mobilize, and Trump marks the U.S. Army's 250th anniversary with a military parade in Washington.

The main demonstration - a "No Kings" march - will be held in Philadelphia, while no protests are scheduled in Washington, D.C., where Trump is set to appear at the parade, which coincides with his 79th birthday and Flag Day.

The protests come amid rising tensions over Trump's recent orders to deploy the National Guard and Marines to Los Angeles following violent clashes sparked by federal immigration raids. Demonstrators blocked highways and torched vehicles, pro...