Donald Trump is ramping up his war on immigrants with a threat to round up “millions” of people. He made the vow on Twitter:

Next week ICE will begin the process of removing the millions of illegal aliens who have illicitly found their way into the United States. They will be removed as fast as they come in. Mexico, using their strong immigration laws, is doing a very good job of stopping people long before they get to our Southern Border. Guatemala is getting ready to sign a Safe-Third Agreement. The only ones who won’t do anything are the Democrats in Congress. They must vote to get rid of the loopholes, and fix asylum! If so, Border Crisis will end quickly!

Even if Trump is serious about this threat, the Washington Post notes, “Large-scale ICE enforcement operations are typically kept secret to avoid tipping off targets.” Experts also say there simply isn’t the manpower to capture millions of people and deport them.

Beyond all that Beto O’Rourke points out, “Militarizing and raiding our communities makes us less, not more, safe.”

Even though the execution of this operation seems a stretch, this isn’t just Twitter talk. The Washington Post says that, “Trump and his senior immigration adviser, Stephen Miller, have been prodding Homeland Security officials to arrest and remove thousands of family members whose deportation orders were expedited by the Justice Department this year as part of a plan known as the “rocket docket.” And the paper adds that acting ICE director Mark Morgan “has said publicly that he plans to beef up interior enforcement and go after families with deportation orders, insisting that the rulings must be carried out to uphold the integrity of the country’s legal system.”

CNN is reporting ICE officials were not aware Trump was going to announce the plan and that there are “not a lot of happy faces” at DHS.