Did you not even read you cited references?

Not that I am complaining. I think it was a bold move that paid off
very, very, well. But denying the nature of the conflict is like
saying the Civil War was fought over slavery. It is fine for your Jr.
High text book but when grow, otherwise intelligent, people try
spouting that stuff they are either American idiots or just don't
care.

To quote from the wikipidia page you cited.

"The Mexican–American War was an armed conflict between the United
States and Mexico from 1846 to 1848 in the wake of the 1845 U.S.
annexation of Texas, which Mexico considered part of its territory
despite the 1836 Texas Revolution.