At Camp Zama, one of my old haunts in my second home town. No one was injured:

There was a scare today at a U.S. military base outside Tokyo when two small explosions occurred shortly after 11 p.m. there. While no one was injured, investigators are looking at the possibility that it was an attempted terrorist attack.

Intelligence reports in Japan and Pakistan suggest al Qaeda has established a small but powerful presence in Japan, which leads some wondering whether or not today’s events are the first attempt at an attack by al Qaeda in Japan.

Pakistani intelligence sources tell ABC News they have had several reports that Pakistani militant organizations working with al Qaeda had established networks in Japan as far back as 1999.

While Islamic terrorism is a legitimate threat in Japan, I doubt that this attack had anything to do with Al Qaeda. There was a similar attack against Zama and also one against Yokota Air Base in the 1990s. In both cases, Japanese nationalists were responsible. There is a small but annoying group of ultranationalists in Japan who resent the US military presence in their country–at their government’s request–and they fling poorly made bombs against our bases around Tokyo once every few years. In the Yokota attack, iirc the terrorists launched a mortar (which was little more than a flaming ball of socks) from a tea field outside the base perimeter fence in an attempt to strike a C-130 parked nearby. The mortar burned a few blades of grass but did no other damage. I suspect that this latest attack springs from the same source.

Update (AP): The Blotter says it could be … Al Qaeda in Japan! Heh.