Okinawa Gov. Hirokazu Nakaima's approval Friday of the start of offshore fill work for building an airstrip to replace U.S. Marine Corps Air Station Futenma angered people opposed to the base to the point that around 1,000 protesters forced their way into the prefectural office and staged a sit-in.

The protesters, who occupied the lobby and formed a human chain outside, called for Nakaima to retract his approval of the fill work and resign.

"Okinawa residents cannot tolerate the base relocation within the prefecture," said Akira Oshiro, a 53-year-old company worker from Urasoe who was among the protesters.