Not the first, won’t be the last.
When I was stationed at Yokota AB in 1986 two rockets were launched at the base. They were aiming at what the bad guys thought were the weapons bunkers. They missed, but came much too close to several of the apartment towers on base.
Shortly after the rocket incident, somebody tried to ram a car through one of the gates.
After that incident, there were large numbers of Japanese riot police stationed at the gates for several months. No more attacks after the police turned out.
I was stationed at Camp Fuchinobe 1965-69. We lived in Minami-Rinkan, midway between NAS Atsugi and Camp Zama. It was pretty peaceful then. Most issues arose from brawling GIs up in the Tokyo area on R&R from Vietnam. Both bases were pretty open.