Which organization is a collective security treaty that the US participates in?

The North Atlantic Treaty Organization (NATO) serves as a prime example of a collective security treaty with United States participation. Established in 1949, NATO was created in response to the geopolitical tensions of the post-World War II era, particularly the threat posed by the Soviet Union. The organization is built on the principle of collective defense, which asserts that an attack against one member is considered an attack against all members.

This principle is reaffirmed in Article 5 of the NATO treaty, which has only been invoked once—in response to the September 11 attacks in 2001. Through NATO, the U.S. engages in military cooperation and security guarantees with its member states, strengthening transatlantic ties and contributing to regional stability.

The other options don't represent collective security treaties that involve the U.S. The World Trade Organization focuses on international trade regulations, the International Monetary Fund centers on global economic stability and financial cooperation, and the World Health Organization addresses public health issues. None of these organizations operate under the collective defense principle that characterizes NATO.