Mexico says Texas may be violating international law by installing a border wall made up of orange buoys in the middle of the Rio Grande in the state’s latest attempt to secure the United States border. Mexico’s Foreign Relations Secretary Alicia Barcena said the move could be violating the Mexican Water Treaty of 1944 between the two countries and may be intruding on Mexico’s territory.

“We have sent a diplomatic letter [to the U.S.] on June 26 because in reality what it is violating is the water treaty of 1944,” Barcena told reporters in Mexico City on Friday, July 14.

Barcena said the country is also sending a team out to inspect the new floating wall to ensure Texas kept the buoys on the United States’ side of the Rio Grande.

Texas Gov. Greg Abbott and the Texas Department of Public Safety, which is overseeing the project, said the goal is to stop migrants who enter the country illegally and make a dangerous trek across the river by implementing the new 1,000-foot barrier near the city of Eagle Pass.

More migrants died at the U.S.-Mexico border last year than ever before – drownings at the Rio Grande are part of the reason why. Earlier in July, four migrants including an infant girl drowned while crossing the river.

Gov. Abbott told Fox News on Friday that Operation Lone Star’s installation of “floating marine barriers in Eagle Pass [will] bolster the state’s historic deterrence efforts.”

“In addition to [razor wire], we now have buoys in the water to prevent people from even crossing the middle part of the Rio Grande River and coming into the state of Texas,” Abott said. “Because Texas has done such a prolific job of stopping people from coming into our state, you are seeing a massive increase in the number of people crossing into New Mexico, Arizona, and California.”

But Texas could be forced to take the buoys down after Mexico filed an official diplomatic complaint to the U.S. Barcena said if the buoys impede the flow of water, that would be a violation of the 1944 Water Treaty which requires the river to remain unobstructed.

In addition to Mexico, other critics of the plan include migrant advocates voicing concerns about drowning risks and environmentalists questioning the impact on the river from the buoys.

The buoy border is the latest effort from Abbott to take the border crisis into his own hands, using state resources where he says federal help has lacked.

The Lone Star State has deployed its own National Guard, built new sections of border wall and has bused more than 20,000 migrants from Texas to big sanctuary cities across the U.S.