The Justice Department (DOJ) announced it plans to sue the state of Texas over the floating buoys the state placed in the Rio Grande earlier in July. The buoys are intended to obstruct the path of illegal migrants from easily entering the country from the southern border.

“We write to inform you…that the United States intends to file [a] legal action in relation to the State of Texas’s unlawful construction of a floating barrier in the Rio Grande River,” Assistant Attorney General Todd Kim and U.S. Attorney Jaime Esparza wrote in a Thursday letter to Gov. Greg Abbott, R-Texas, and Interim Texas Attorney General Angela Colmenero. “The State of Texas’s actions violate federal law, raise humanitarian concerns, present serious risks to public safety and the environment, and may interfere with the federal government’s ability to carry out its official duties.”

Specifically, the department said Texas’ placement of buoys in the Rio Grande may violate the Rivers and Harbors Act. In the letter, the DOJ wrote that if Texas fails to “expeditiously remove” the buoys by 2:00 p.m. on Monday, July 24, “the United States intends to file legal action.”

The buoy barrier is roughly 1,000 feet in length, situated near the border town of Eagle Pass. It’s the latest effort in Gov. Abbot’s plan to stop the flow of illegal migration through an initiative known as Operation Lone Star.

“The tragic humanitarian crisis on the border was created because of Biden’s refusal to secure the border. His open border policies encourage migrants to risk their lives crossing illegally through the Rio Grande, instead of safely and legally over a bridge,” Abbott said in a Twitter thread on Friday, July 21. “Texas has the sovereign authority to defend our border, under the U.S. Constitution and the Texas Constitution. We have sent the Biden Administration numerous letters detailing our authority, including the one I hand-delivered to President Biden earlier this year.”