The North Atlantic Treaty Organization is a UN-affiliated military alliance, and the troops placed under NATO command, including U.S. troops, serve as a UN, not a U.S., army. Under NATO’s Article 5, “The Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all and consequently they agree that, if such an armed attack occurs, each of them … will assist the Party or Parties so attacked.”