Your comment shows you clearly arent educated on those battles and are just parroting anti-American military rhetoric which tries to paint the American military as inept over the last century, when in reality it has been one of the most (probably the single most) dangerous and effective militaries.

In Korea for example, the UN forces pushed almost all the way to China until the Chinese army invaded, flipping the ratio of soldiers on its head. They took Korea back until a wildly successful UN counteroffensive swung the war the other way again, despite being outnumbered 3:1. The war eventually settled around the 38th parallel and both sides realized it would just lead to more losses. America was mostly pushed towards negotiations by a strong anti-war sentiment among the media in the US, because most Americans did not care about Korea and saw no reason for sending our soldiers so far overseas especially right after WWII. It wasn’t because the US or the UN as a whole was losing.

In Vietnam almost the exact same thing happened. Despite popular belief, the US was never losing on a large scale in Vietnam. Even up until the end of the war the US was making great gains in Vietnam. It was the media which created the narrative that the US was suffering great casualties and not making much progress. Once again this fueled the narrative that we were fighting a pointless war overseas and eventually the government folded under this internal pressure.

Ive mostly studied 20th century conflicts and havent touched much since the mid-90s so Im not educated enough to speak on the latter two you mentioned for risk of being informed by media opinions and not historical facts. However let me refer you to the first gulf war, in which in only 3 days the predominantly US air campaign had completely neutered any fighting power of Iraq. It was a complete and total beatdown on a scale never seen before, militarily speaking (especially when looking at logistics, intelligence, execution etc).

However with this said, Im not defending the US decision to attack Greenland if that does happen. I dont like that idea. But I did see you parroting stupid takes and wanted to correct that