An assailant threw a homemade firebomb into the US consulate compound on the southern Japanese island of Okinawa, home to most of the American troops based in Japan, but nobody was injured in the attack, police said.
The Molotov cocktail fell in the garden inside the compound and burned itself out, Okinawan police official Yasuhiko Yoshinaga said. He declined to give further details.
A local resident told police that a person driving a black motorbike fled the scene after the attack.
Okinawa, located 1,600 kilometers (1,000 miles) south of Tokyo, is home to more than half the 50,000 U.S. troops based in Japan and is considered a linchpin in the American military posture in Asia.
There has long been anti-US military sentiment on the island, with Okinawans complaining of soldier-related crimes.