The Department of Justice has sued Texas Gov. Greg Abbott following the governor's refusal to remove a stretch of inflatable buoys on the Rio Grande, which sits between his state and Mexico.

The lawsuit accuses the state of violating the River and Harbors Act, which prohibits the placement of obstructions in the water without federal approval.

"We intend to seek the appropriate legal remedies, including the removal of such obstructions in the Rio Grande," Assistant Attorney General Todd Kim said in a statement.

Last week, the U.S. Department of Justice warned Abbott that he had until Monday afternoon to agree to remove the barrier or face legal action. Officials said the governor's efforts to hinder migrants from crossing into Texas were "unlawful" and presented "humanitarian concerns," Texas Public Radio reported.

In a letter to President Biden on Monday, Abbott remained firm on his decision to deploy the buoys, insisting that Texas had the authority to enforce border security measures on its border.

"Texas will see you in court, Mr. President," he said.

The 1,000-foot-long floating barrier was installed near the border town Eagle Pass in early July as part of Abbott's $4 billion border security initiative, Operation Lone Star.

Texas' stretch of buoys covers only a tiny fraction of the 1,254 mile-river. To put in perspective, 1,000 feet is only about a fifth of a mile.

What is the floating barrier supposed to achieve?

The barrier is about 4 feet tall and movable, so that it can be "deployed strategically" in migrant crossing hotspots, Abbott said at a press conference in June. Webbing is also attached to the barrier underwater to make it difficult to swim below.

Still, it's not impossible to pass through the buoys. But Abbott said the floating border wall is designed to deter large groups of people from reaching Texas.

The Rio Grande is considered one of the deadliest travel routes for migrants. Over the years, its fast-flowing waters have drowned and killed hundreds of people attempting to reach the U.S., including babies and children.

Abbott said preventing more deaths is one reason for the buoys. But immigration advocates disagree that it will stop migrants from crossing. Rather, they argue the barrier will make the situation more dangerous for people who try to do so.

DOJ, U.S. lawmakers, Mexico urge the buoys to be removed

The DOJ on Thursday said Texas is violating the Rivers and Harbors Act by installing the barrier without federal approval.

Similarly, earlier this month, Mexico's top diplomat Alicia Bárcena said the buoys may violate 1944 and 1970 treaties on boundaries and water, particularly if it impedes the flow of water. Mexico has also asked for the buoys to be removed.

On Friday, dozens of House Democrats urged President Biden to stop Texas from deploying the buoy wall and sharp razor wire in the Rio Grande. They described the measures as creating "death traps" for migrants.

"As Governor Abbott continues to escalate his efforts on the border, we urge you to take the above actions and stop this horrific abuse of power," the letter said, which was led by Texas Congressman Joaquin Castro.

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