Saddam Hussein invaded Kuwait in 1990 and as a result, controlled its oil. Kuwait was one of the countries supplying the U.S. and so if Hussein decided to shut down Kuwait oil, the U.S. would be affected.
Hussein's aggressive actions also threatened the security of U.S. allies like Saudi Arabia which they actually tried to invade during the Battle of Khafji. Kuwait was also a strategic importance as they are located in the Persian gulf which would give the U.S. access to waters close to Iran.
The Republican Henry Cabot Lodge and other Republicans refused to ratify the League of Nations because certain aspects of the new international organization were believed to interfere with American sovereignty in crafting foreign policy
