President Donald Trump said Saturday that his administration is considering imposing a two-week, large-scale quarantine of New York, New Jersey, and certain parts of Connecticut in an effort to stop the spread of the coronavirus. Trump said that a decision could come as early as Saturday but he gave few details of what an order of that nature would entail and experts aren’t clear whether the president even has the power to order state residents to not travel.

“We might not have to do it but there’s a possibility that sometime today we’ll do a quarantine — short-term, two weeks — for New York, probably New Jersey, certain parts of Connecticut,” Trump told reporters on Saturday afternoon. Trump specified it would be an “enforceable” quarantine. The president said he was particularly concerned after talking to Florida Gov. Ron DeSantis because “a lot of New Yorkers are going” to Florida and “we don’t want that.”

Trump said he was having “very good dialogue” with New York Gov. Andrew Cuomo. But when Cuomo was asked about the president’s quarantine warning during a news conference, the New York governor said the issue had not come up when he talked with Trump earlier in the day. “I don’t even know what that means,” the governor said. “I don’t know how that could be legally enforceable and from a medical point of view, I don’t know what you would be accomplishing. But I can tell you I don’t even like the sound of it.”

Although the federal government can take measures to prevent diseases from spreading between states, experts aren’t quite sure that gives Trump the necessary authority to block people from leaving a state. Courts have long ruled that it is largely up to states to order quarantines but they also generally side with public health officials. Lawrence Gostin, a Georgetown University law professor and public health specialist said that it “it is entirely unprecedented that governors or the president would prevent people from traveling from one state to another during an infectious disease outbreak.” In order to avoid a legal battle, Trump may end up telling residents of those states to self-quarantine and not travel without a risk of penalty if they don’t comply.

Several states, including Florida, Rhode Island, South Carolina, Maryland, and Texas have already called on people arriving from the New York area to undergo a 14-day self-quarantine.