Two individual ones. USA has individual bilateral security agreements with both. "Treaty of Mutual Cooperation and Security between the United States and Japan

Two individual ones. USA has individual bilateral security agreements with both. "Treaty of Mutual Cooperation and Security between the United States and Japan" or just the US-Japan Security treaty [0] "Mutual Defense Treaty (United States–South Korea)" [1] https://en.wikipedia.org/wiki/Treaty_of_Mutual_Cooperation_and_Security_between_the_United_States_and_Japan#:~:text=The%20Treaty%20of%20Mutual%20Cooperation%20and%20Security%20between,%22in%20the%20territories%20under%20the%20administration%20of%20Japan%22 https://en.wikipedia.org/wiki/Treaty_of_Mutual_Cooperation_a.... https://en.wikipedia.org/wiki/Mutual_Defense_Treaty_(United_States%E2%80%93South_Korea) https://en.wikipedia.org/wiki/Mutual_Defense_Treaty_(United_...