JK of course. Many think of me as a wuss till they piss me off.
We didn't steal half of mexico, they lost the war and then signed the treaty. Not only that but they WANTED to sell most of Sonora and Baja California. We should have taken it.
Conquest of large portions of land by one soveriegn from another is not theft unless the conquering army is repulsed or defeated later. History is always told from the POV of the victor.
If you can't hold it you deserve to lose it, but these days it's more or less impossible to forcibly annex territory. For better or worse, the international system is now too strong for a nation to completely ignore. The good old days of invading, conquering, and annexing are over.
Your Singapore example is stupid. Times have changed too much for any example like that to be relevant.
Half the world would be up in arms against us if we did that.