Two explosions near a U.S. military base in Zama, Kanagawa Prefecture, late Monday could be the first attempt by the al-Qaida network to launch an attack in Japan, ABC News reported on its Web site.
ABC News said intelligence reports in Japan and Pakistan suggest al-Qaida has established "a small but powerful presence" in Japan, leading "some wondering whether or not today's events are the first attempt at an attack by al-Qaida in Japan."
Police said two explosions were reported late Monday near Camp Zama by local residents. No one was injured.
Police found two metal tubes, one apparently a mortar launcher, at a nearby park.
Leftwing Japanese groups have used this exact method against U.S. bases in the past.
Quoting Pakistani intelligence, ABC News said it has had several reports that Pakistani militant organizations working with al-Qaida had established networks in Japan as far back as 1999.
These networks were set up following the direct orders of Khalid Sheik Mohammad, the top al-Qaida leader now in U.S. custody at Guantanamo Bay, who had a "deep interest" in conducting operations inside Japan, it said, quoting a Pakistani intelligence source.
The source also said around two dozen Pakistanis had been sent to Japan on student visas in the late 1990s to set up "sleeper cells" and they had linked with operatives from the leading Indonesian terrorist group, Jemaah Islamiyah, according to ABC News.
"If these explosions turn out to have been terrorist attacks, these networks are the first place to look," the source was quoted as saying.