Deep-cut case law and 19th century constitutional interpretation underpin the Trump administration argument for deploying troops to Los Angeles.

PHILADELPHIA (AP) — Cities large and small were preparing for major demonstrations Saturday across the U.S. against President Donald Trump, as officials urge calm, National Guard troops mobilize and Trump attends a military parade in Washington to mark the Army’s 250th anniversary.

They are trying to strike a careful balance on issues where Republicans have held a political advantage in recent years.

When Immigration and Customs Enforcement agents raided worksites in Los Angeles on June 6, randomly arresting and detaining undocumented and legal immigrants, these new and invasive tactics of immigration enforcement provoked protests.

Trump followed that up with a campaign-style rally at Fort Bragg in North Carolina, where uniformed soldiers cheered as he slammed former President Joe Biden, Newsom and other Democrats — raising concerns the president was using the military as a political prop.

California is challenging President Trump's decision to deploy federal troops to assist immigration agents in Los Angeles.

U.S. Marines will deploy to Los Angeles streets within 48 hours with authority to detain civilians, escalating federal-state tensions as California sues to block military involvement in immigration enforcement.