The U.S. Department of Justice sued three states—Connecticut, New York and Vermont—over their policies allowing undocumented students to pay in-state tuition, the Trump administration announced Monday.

“This is a simple matter of federal law: colleges cannot provide benefits to illegal aliens that they do not provide to U.S. citizens,” Assistant Attorney General Brett A. Shumate of the Justice Department’s Civil Division said in a news release. “This Department of Justice will not tolerate American students being treated like second-class citizens in their own country.”

The federal government has now filed 17 lawsuits against states that hold such policies. Some states, such as Nebraska, Oklahoma and Texas, swiftly sided with the federal government and ended their in-state tuition policies, while others continue to fight the lawsuits. Minnesota won its case this spring, though the DOJ has since appealed the decision. A federal judge recently decided in favor of the DOJ in Illinois.

Associate Attorney General Stanley Woodward said in the release that the DOJ has now sued “every state in the [U.S. Court of Appeals for the] Second Circuit that seeks to thwart Congress’s clear prohibition by placing alien over citizen.”

“Our efforts will not cease until President Trump’s promise is fulfilled: illegal aliens will not receive benefits denied to our Nation’s own citizens,” he said.