Opponents of President Donald Trump ’s administration are set to rally in hundreds of cities on Saturday during the military parade in Washington for the Army’s 250th anniversary — which coincides with Trump’s birthday — as protests grow in response to his immigration policies.

U.S. Marines will join National Guard troops on the streets of Los Angeles within two days, officials said on Wednesday, and would be authorized to detain anyone who interferes with immigration officers on raids or protesters who confront federal agents.

The demonstrations coincide with a Flag Day military parade in Washington honoring the U.S. Army’s 250th birthday.

Police arrested more than 20 people, mostly on curfew violations, on the first night of restrictions in downtown Los Angeles.