Texas Gov. Greg Abbott has no constitutional authority to define the flow of undocumented immigrants across the Rio Grande as an “invasion” and is usurping powers that belong to the federal government, the U.S. Justice Department says in new court filings.

“Whether and when an ‘invasion’ occurs is a matter of foreign policy and national defense, which the Constitution specifically commits to the federal government,” the Justice Department wrote in a 13-page brief that included nearly 150 pages of supporting material.

“An invasion is ‘armed hostility from another political entity, such as another state or foreign country that is intending to overthrow the state’s government,'” the Justice Department added, citing a 1996 decision by the Supreme Court.

The brief, filed late Wednesday in the Western District of Texas, is part of the ongoing litigation brought by the Justice Department against Abbott and the state of Texas over the placement of giant buoys in the Rio Grande near Eagle Pass to deter unlawful immigration. The Justice Department is asking Senior U.S. Judge David Alan Ezra to order the buoys removed pending the outcome of the trial, which has yet to begin.

A hearing on the matter is set for Tuesday in Austin.

Texas border barrier like waging war: legal filing

An earlier filing by lawyers for Abbott and the state defended the placement of the 1,000-foot string of floating barriers, saying governors have broad powers to act without federal authority to defend against an invasion.

And in public remarks and social media posts, Abbott has called the sharp increase in unlawful border crossings, coupled with transnational drug-trafficking, an invasion that threatens Texas’ sovereignty.

“The federal government’s FAILURE to secure our border has forced Texas to protect its own territory against invasion by the Mexican drug cartels & mass illegal immigration,” said in one tweet from his official government account.

In a “friend of the court” brief filed this week by attorney Matt Crapo of the conservative Immigration Reform Law Institute in support of Texas’ position, the rhetoric was even more heated.