Federal troops are patrolling the National Mall and neighborhoods across Washington in President Donald Trump’s extraordinary takeover of the police department in the nation’s capital.

Now the Trump administration is moving to install its own emergency police commissioner, a big step forward in one of the most sweeping uses of federal authority over a local government in modern times.

While Washington went to court on Friday to block Trump’s takeover, how it will play out and whether the federal government views this as a potential blueprint for dealing with other cities remains up in the air. Here’s what to know about the situation and what might come next:

Why is Trump taking over the police in DC?

The Republican president this week announced he’s taking control over Washington’s police department and activating National Guard troops to reduce crime, an escalation of his aggressive approach to law enforcement. But District of Columbia officials say the action isn’t needed, pointing out that violent crime in the district reached historic 30-year lows last year and is down significantly again this year.

Can he do that?

D.C.’s status as a congressionally established federal district gives Trump a window to assert more control over the the district than other cities. D.C. Mayor Muriel Bowser didn’t offer much resistance at first, allowing city workers to clear homeless encampments and work closely with federal immigration agents. But on Friday, the heavily Democratic district asked for an emergency court order blocking Trump officials from putting a federal official in charge of D.C. police.

So who is in charge of police in Washington?

Right now, it’s unsettled. Trump’s administration announced Thursday that the head of the Drug Enforcement Administration will take over the police chief’s duties, including authority over orders issued to officers. It’s unclear where the move leaves the city’s current police chief, Pamela Smith, who works for the mayor. Smith says upending the command structure would be a “dangerous” threat to law and order.

What’s at stake

The showdown in Washington is the latest attempt by Trump to test the boundaries of his legal authority to carry out his tough-on-crime agenda, relying on obscure statutes and a supposed state of emergency to speed up the mass deportation of people in the United States illegally.

What are the federal troops doing in DC?

About 800 National Guard troops are being activated, with Humvees parked along the Washington Monument and near Union Station. Troops have been spotted standing outside baseball’s Nationals Park and neighborhood restaurants. The White House says guard members aren’t making arrests but are protecting law enforcement officers who are making arrests and helping deter violent crime. Trump says one of the objectives will be moving homeless people far from the city.

How long can this go on?

Trump has the authority to do this for 30 days and says he might look into extending it. But that would require congressional approval. Whether Republicans in Congress would go along with that is unclear. Some D.C. residents have protested against the increased police presence. For some, the action echoes uncomfortable historical chapters when politicians used language to paint predominantly Black cities with racist narratives to shape public opinion and justify police action.

Will Trump try to take control in other US cities?

Washington is very different from any other American city, and the rules that govern it give the federal government much more control than it would have anywhere else. Whether Trump is using this as a blueprint for how to approach cities — largely Democratic cities — that he wants to exert more control over remains to be seen.