The historical record is that the United States got approval from the UN because in the post-World War 2 world there is international law.
Harry Truman ran right to the UN Security Council in 1950 got approval from them and called Korea a “police action.” Our troops were under United Nations command then, although led by American generals.
In Irag in particular, there was all this need to get the UN involved before and after the military actions.
In Afghanistan right now our soldiers are part of the UN sanctioned International Security and Assistance Force. UN backing was sought as soon as possible after the military actions following 9-11.
I support our troops, but they fight under international command right now in Afghanistan. That’s the stark reality.
You misunderstand UN approval and assistance.
The UN has no bearing on whether the US intervenes in an area.
There is no taking away of sovereignty if the UN agree on an action...none.
We went to both Afghanistan and Iraq due to US presidential action and congressional approval.