Countries have largely stopped declaring war even when they send troops to overthrow a county. It's the kind of distiction the only matters in international politics.
Well if that was throwntoday's point, it's a distinction without a difference. The Korean War particularly, despite not being officially declared as a war, came disturbingly close to going nuclear.
To underscore how silly this is the last time the US “declared” war was 1942. https://en.wikipedia.org/wiki/Declaration_of_war_by_the_Unit...