In all seriousness, America does not pull their weapon to prevent bad things from happening (or at least, not primarily).
The US primarily works through Nato and the UN to intervene in their 'world police' role, but they are happy to start other conflicts without the support of Nato and the UN (see Afghanistan, Iraq, Vietnam, ~~Korea~~).
If the US were really the 'world police', then where were they in Rwanda, in Sudan, in North Korea, in Sri Lanka, in Nigeria, in Myanmar, in DRC, in Ethopia, what are they doing for the Uyghurs, the Rohingyas...
EDIT: see correction from OfSanguineFire, I was wrong about Korea, which was indeed a UN-led intervention.
The US involvement in the Korean War was organized under the nascent UN.[0] "During the course of the war, 22 nations contributed military or medical personnel to UN Command. Although the United States led the UNC and provided the bulk of its troops and funding, all participants formally fought under the auspices of the UN, with the operation classified as a 'UN-led police action'."
In all seriousness, America does not pull their weapon to prevent bad things from happening (or at least, not primarily).
The US primarily works through Nato and the UN to intervene in their 'world police' role, but they are happy to start other conflicts without the support of Nato and the UN (see Afghanistan, Iraq, Vietnam, ~~Korea~~).
If the US were really the 'world police', then where were they in Rwanda, in Sudan, in North Korea, in Sri Lanka, in Nigeria, in Myanmar, in DRC, in Ethopia, what are they doing for the Uyghurs, the Rohingyas...
EDIT: see correction from OfSanguineFire, I was wrong about Korea, which was indeed a UN-led intervention.