WASHINGTON — The Justice Department informed Texas in a letter Thursday that it intends to sue the state for placing buoys in the Rio Grande to deter immigrants unless the state acts to remove them.

«We are writing to inform you… that the United States intends to prosecute the state of Texas’ illegal construction of a floating barrier on the Rio Grande River,» Assistant Attorney General Todd Kim and U.S. Attorney Jaime Esparza wrote in the letter obtained by NBC News.

The letter, sent to Texas Governor Greg Abbott and Acting Texas Attorney General Angela Colmenero, both Republicans., says the state’s actions violate the Law of Rivers and Portsendanger public safety and could obstruct the official duties of the federal government.

Texas began building the buoys earlier this month, as part of Abbot’s $4 billion effort to counter migration, Operation Lone Star, which also includes busing thousands of migrants to Democratic-led cities and Arrest of immigrants for trespassing.

Some immigrant advocates have warned that the buoys could cause people to drown. The Justice Department letter echoes that warning, saying the barriers obstruct the «navigation capacity» of the river and present «humanitarian concerns».

in a cheep On Friday, Abbott said Texas has the «sovereign authority» to defend its border and accused the Biden administration of exacerbating conditions along the southern border.

“We will continue to implement all strategies to protect Texans and Americans, and migrants who risk their lives,” Abbott wrote. «See you in court, Mr. President.»

Abbot’s office did not immediately respond to NBC News’ request for comment.

The letter asks the state to provide a response stating that Texas commits to «expeditiously remove» the buoys by 2:00 p.m. Monday. If the state does not produce such a response, «The United States intends to take legal action,» the letter state

The letter represents the latest DOJ investigation into Texas immigration policies. On Thursday, a Justice Department spokesperson told NBC News that the department is investigating allegations made by a Texas police officer in an email to his superiors, in which he described how he and his partner were ordered to push migrants into the Rio Grande River and were denied water despite the blistering heat.

Texas Department of Public Safety officials have denied the existence of any directive, policy or order directing troops to push migrants back into the river or deny them drinking water.

nicole acevedo contributed.