President Donald Trump said on Monday that he would be issuing an executive order to “temporarily suspend immigration into the United States” in light of the lingering threat of the new coronavirus.

The announcement, which would represent one of the most dramatic moves by a president over immigration policy in modern memory, was made via Twitter. The White House did not provide any immediate clarification, including when such an EO would be signed, which Trump did not specify in his tweet.

Presidents enjoy wide latitude when it comes to unilaterally setting immigration policy, as affirmed by the courts. But it’s unclear if a blanket shutdown of all immigration would pass legal muster, or if that is what Trump is even proposing. The devil will be in the details, as is usually the case with this administration. Trump’s previous bans, including those involving China and Europe as the coronavirus spread, were porous and contained exceptions for citizens (which won’t matter here) and trade interests (which very well could).

Trump’s team is made up of immigration restrictionists, most notably top aide Stephen Miller. And it has proposed reducing legal immigration before. The onset of the coronavirus pandemic has emboldened this mindset among the president and his aides, as they seek to close borders to stem the flow of the virus, implement more hard-line immigration policies, and craft a new vision for the domestic economy. At one point, Trump’s commerce secretary, Wilbur Ross, even predicted that the coronavirus would result in job growth in America as consumers began turning to domestic suppliers and trusting them more.

That obviously did not happen. Job loss has skyrocketed as the pandemic has shut down much of the country. And it’s hard to see how stopping immigration entirely would alleviate that fundamental problem, as not many people are likely immigrating anywhere at the moment, with travel coming to a halt and the pandemic being global and all. Nevertheless, the most committed of Trump supporters embraced his tweet as an act of divine political wisdom.

Trump’s promise to sign an executive order “in light of”—as he put it—“the attack from the Invisible Enemy” comes as he is enduring continued criticism over the federal government’s inability to stand up a robust testing regime. It also is coming roughly the same time that he has begun encouraging states to consider reopening their economies and loosening social distancing guidelines because of the progress he says has been made in combating coronavirus.