The United States belongs to the following international associations from your list:
- United Nations: The U.S. is a founding member and plays a significant role in this international organization.
- North Atlantic Treaty Organization (NATO): The U.S. is a founding member of NATO, a military alliance established for collective defense.
The United States does not belong to the Warsaw Pact or the League of Nations (which was replaced by the United Nations). The British Commonwealth is a political association of mostly former territories of the British Empire, and while the U.S. has historical ties, it is not a member in the same way that Commonwealth nations are.