WASHINGTON, Oct 4 (Reuters) - Fighter jets from the United States and Japan carried out joint drills on Tuesday over the Sea of Japan following North Korea's first test-firing of a ballistic missile over Japan in five years, the U.S. military said."Our commitment to the defense of the Republic of Korea and Japan remains ironclad," the Hawaii-based U.S. Indo-Pacific Command said in a statement, adding the drill was carried out by U.S. Marine Corps fighter jets that joined Japan Air Self-Defense Force (JASDF) fighter jets.Register now for FREE unlimited access to Reuters.comOur Standards: The Thomson Reuters Trust Principles."