Texas governor Greg Abbott has gone and done it again, aggressively preempting federal authority to manage our international boundary with Mexico. This time, instead of lines of shipping containers, steel fences and miles of concertina wire, it’s floating chains of buoy-anchored, rotating jumbo-balls down the center of the Rio Grande River, designed to prevent swimmers and floaters from reaching Texas’s shore.

Abbott’s justification for this patently political act is that it will save lives. That’s a bit rich, given his apparent lack of concern for desperate migrants lacerating themselves while weaving through razor wire or risking injury and death descending the 30-foot metal fences now being erected under Operation Lone Star.

But whether or not Abbott’s concern for migrants is at all sincere, his aggressive new migrant prevention measure brazenly flouts the international treaty governing the management of the Rio Grande River.

The Treaty to Resolve Pending Boundary Differences and Maintain the Rio Grande and Colorado River as the International Boundary, signed in 1970, sets limits on how the two countries can manage the Rio Grande. Most particularly, the treaty prevents any one country from unilaterally taking measures that would displace the boundary or impair its integrity. Any such measures, including the construction of levees or other barriers along the river in its reach from El Paso to Brownsville, require the approval of both the U.S. and Mexican governments.

Two conditions are cardinal to the 1970 Boundary Treaty. First, in accordance with both domestic and international law, adherence to the treaty is a national obligation that binds the affected states. States have no independent authority in the matter of treaty adherence and enforcement. Second, any proposed barriers with the potential to impair the boundary can only proceed as a joint decision of the parties as a joint decision of the parties. These are binding rules, not principles or guidelines.

Governor Abbott’s new barrier violates both of these rules. The International Boundary and Water Commission’s U.S. Section, charged with enforcing and implementing the 1970 treaty, says it was not consulted. If the U.S. Section wasn’t consulted, you can bet the Mexican Section was left in the dark too.

Nor is this the first time Abbott’s ignored international law. He looked the other way when the now notorious We Built the Wall group (of Steve Bannon fame) built bollard-style fencing on the banks of the Rio Grande absent any prior consultation with the IBWC or Mexican approval. That project, parts of which are now in danger of collapsing in the river, was sued by the federal attorney for the Southern District of Texas for treaty violation, forcing Fisher Sand and Gravel, the contractor, to settle the case and assume responsibility for any damages that occur. 

Did that deter Abbott? No. He recently hired Fisher to build the 9-mile steel fence segment of his Operation Lone Star wall.

Abbott’s latest barrier concoction, which he proposes to install at various migrant hot-spots along the river, similarly violates the boundary treaty. Moored by buoys, the bobbing balls and the underwater skirt they support risk catching debris and obstructing the natural river. There’s no telling what will occur under flood conditions should powerful flows pack more debris in the buoy-skirts at river pivots, deflecting water into Mexico and threatening the integrity of the river’s course.

And then there’s the problem of preempting the IBWC’s authority to establish and maintain the boundary in the center of the river. It’s not at all clear just how Abbott’s team intends to place the bobbing barrier and whether it can reliably sit just shy of the river’s center in U.S. sovereign jurisdiction, or whether it impedes the IBWC’s ability to manage the boundary channel.

The most immediate violation, however, is simply the failure to consult with either the IBWC or U.S. federal officials in deploying these tethered balls in the river. That is not just insulting to Mexico, it’s downright unlawful.

Abbott’s willingness to play the Texas sovereignty card and exploit the migrant crisis for political gain is hardly a secret. His willingness to ignore international obligations as he grandstands on the backs of desperate people is not just an international embarrassment complicating our relations with Mexico — it’s a disgrace. We can only hope the IBWC’s U.S. section and federal attorneys in the Southern District of Texas are watching closely.

Stephen Mumme is author of “Border Water: : The Politics of U.S.-Mexico Transboundary Water Management, 1945–2015″ and a professor of political science at Colorado State University.