The Ground Self-Defense Force found what appears to be a projectile Thursday in a parking lot at the GSDF Asaka base straddling the Tokyo-Saitama Prefecture border, following the discovery of a suspected homemade mortar at a nearby park the previous night.
Police investigating the case say leftist extremists may have used the device to launch the projectiles at the GSDF facility. Nearby residents reported hearing two explosions Wednesday night, police said.
GSDF personnel discovered the spherical metal object, about 6 cm in diameter, at 7 a.m. Thursday. Police said it may have been fired from the park.
Late Wednesday night, police found two metal pipes partly buried in the ground at Oizumi-Chuo Park in Nerima Ward that were pointed toward the base, which is just north of the park.
Police found the launchers inside a fenced-off area while they were investigating a fire that burned some 6,000 sq. meters of dry grass in the park. Residents near the park alerted police to the fire late Wednesday.
There were no injuries resulting from the incident.
On Monday, two metal projectiles were fired from a public park in Zama, Kanagawa Prefecture, toward a nearby U.S. Army base. One of the projectiles hit the roof of a residential building, but nobody was injured.
Tokyo police said the launcher found in the Oizumi-Chuo Park was similar to the one found in the Zama park, and they appeared to have been used by the same party.