In April, there was a post. “We will keep escalating consequences, including TARIFFS and, maybe even SANCTIONS, until Mexico honors the Treaty, and GIVES TEXAS THE WATER THEY ARE OWED!” President Donald Trump wrote on his Truth Social account. The president’s signature declarative, all-caps style had collided with the highly technical realm of water negotiations between the United States and Mexico. It’s a world governed by an 81-year-old treaty that binds the two neighbors’ taps at a time when water is increasingly scarce on the border.