Not to mention that even if they had claim they held Texas for 10 years and the rest for 20. The U.S. has held it for going on 170 years. We’ve also paid them money I believe too.
They want to say they own something acquired by conquest (and not even by them), yet they don’t want to acknowledge that we have held that territory by conquest nearly 10X longer than they have.
They have no claim.
Texas is a different situation. The Kingdom of New Mexico is a territory that Mexico didn’t have the slightest claim on.