Gee, I don't know.
Annexing an independent democratic republic which existed as such for 10 years and which pettitioned the US for annexation, isn't the same as forcibly annexing a country against the will of said citizens. And as I previously wrote, the US was not a world power at the time. It was a backwater. The big military powers were in Europe. At that time the US was a young fledgling country. Mexico had recognized Texas as an independent state in the years preceeding the Mexican American War.
And let me remind you, the issue here was my statement powerful countries don't forcibly annex their neighbors and your use of Texas in an attempt to refute that claim. The annexation of Texas wasn't by any stretch forcible. The US didn't forcibly annex Texas nor was the US a powerful country by the standards of that time. And let's not forget, that event happened nearly 2 centuries ago.