the US has a long history of a love-hate relationship with Texas.
For example, when Texas fought for it’s independance, officially the US sided with the Texicans, but in secret they were supporting the Mexican dictator, running guns (giving them) to them via the navy.
Yes, that’s right, using US Naval ships to carry guns and gunpowder to the mexican army!
How do we know? A Texican sloop out of Galveston captured the US Navy ship. When Texas joined the Union (some number of years later) one of the settlements was that Texas had to give the US government it’s ship back.
So, at/around that time, the Mexican state was a Vassal of the US, and not a nice one either. (officially they were aligned with Spain)
Sam Houston was trying to make it to La, where President Jackson had stationed a large contingent of US troops. Houston then planned to annihilate Mexican forces with the aid of US troops. The US was solidly on the side of the Texans.