A US F-15 fighter jet crashed into the sea off Okinawa in Japan's on Monday, with a Maritime Self-Defense Force (MSDF) helicopter rescuing the pilot, according to government officials here.

The crash of the F-15 jet, which belonged to the US Kadena Air Base, occurred at around 6:40 a.m. local time and around 80 km south of Okinawa's prefectural capital of Naha, the officials said.

According to sources close to the matter, the condition of the pilot who was rescued by the Japanese side after ejecting from the jet remains unknown.

Okinawa hosts the bulk of the US military bases and assets in Japan, yet the island accounts for just a fraction of Japan's total land mass, Xinhua reported.

There have been mounting calls from officials and locals on the island to have their base hosting burdens reduced with the latest crash of a fighter jet doing little to help ease concerns about the safety of the US military assets in Okinawa.

In May 2013, an F-15 fighter crashed into the sea off Okinawa.