In 1840 we should have executed their government officials when we had them in our custody, and annexed the entirety of Mexico.
As usual.. the pacifists were wrong.
Mexican business leaders & other local leaders approached Winfield Scott at the close of the Mexican War when he was CIC of the army occupying Mexico City. He declined for the US, they then tried to persuade him to leave the US Army and become the head of the Mexican government. He declined that also.