The New York Police Department has activated its Joint Operations Center in coordination with FBI, state, local and federal partners ahead of what is expected to be widespread protests Saturday across the city.

Some 34,000 members of the NYPD will be on the streets of New York City over the next 24 hours.

"You do not have a right to engage in violence and lawlessness," Mayor Eric Adams said in a news conference yesterday ahead of the planned protests.

United States Army North confirmed to ABC News that Marines at the Wilshire Federal Building have made the first temporary detention among the troops sent to Los Angeles on Friday.

In an interview earlier in the week, Maj. Gen. Scott Sherman -- the commander of Joint Task Force 51 -- said, "We're there to protect their federal officers, their federal personnel.”

If those personnel are assaulted, Sherman said, "Soldiers or Marines are allowed to take that person, detain them in place, wait for the federal law enforcement officer to come and arrest that individual."

It was not immediately clear what led to the detainment on Friday.

-ABC News' Luis Martinez

About 200 Marines are taking over responsibility for protecting the Wilshire Federal Building in Los Angeles, Maj. Gen. Scott Sherman told reporters Friday.

The addition of those troops will allow more National Guardsmen to be trained to accompany federal personnel during Immigration and Customs Enforcement raids, according to Sherman.

“The soldiers that were performing those duties will then transition to providing protection to federal law enforcement officers as they conduct their law enforcement function,” Sherman said. “I would like to emphasize that the soldiers will not participate in law enforcement activities. Rather, they'll be focused on protecting federal law enforcement personnel."

Sherman serves as the commander of Joint Task Force 51, the command headquarters for the 4,000 federalized National Guardsmen and 700 Marines assigned to protect federal personnel and property in Los Angeles.

In an interview with ABC and the Associated Press earlier this week, Sherman said, as of then, about 500 of the 4,000 National Guardsmen assigned to the LA area had been specifically trained to work with ICE teams.

-ABC News' Luis Martinez

Marines are now on duty in Los Angeles for the first time. Some were spotted guarding the Wilshire Federal Building on Friday.

President Donald Trump is defending his decision to send the National Guard into Los Angeles and said California Gov. Gavin Newsom should be "happy."

"He should only be happy I sent in the military, because if I didn't send them and you would’ve had a problem, they're the likes of which we haven't seen in a long time," Trump said at a roundtable Monday.

Trump implied that the situation in LA is improving.

"It's lucky for the people in Los Angeles and in California that we did what we did. We got it just in time," Trump said. "It's still simmering a little bit, but not very much."

In 2020, Trump said at an ABC News town hall that "we can't call in the National Guard" to cities "unless we're requested by a governor."

Trump’s comments came after he sought to respond to racial justice demonstrations in cities in the summer of 2020.

"I can call insurrection but there's no reason to ever do that," Trump said at the time.

On Monday, when asked by ABC News what’s changed since 2020, Trump said that the National Guard shouldn't be sent in without approval from local officials but the difference is that California has an "incompetent governor."

"He's destroying one of our great states. And if I didn't get involved, if we didn't bring the guard -- and we would bring more in if we needed it -- because we have to make sure there's going to be law and order," Trump said.

-ABC News’ Michelle Stoddart, Ben Siegel and Karen Travers