Tokyo, October 29 (RHC)-- The Japanese government has resumed the controversial expansion of a U.S. base on Okinawa Island in a move that is set to trigger more and more protests by area residents.

At the heart of tensions is the central government's row with the islanders over the planned relocation of the Futenma base to the Henoko area north of the island.

On Thursday, police dragged away protesters as the government began landfill work in Henoko to prepare the site for the move, a day after overriding Okinawa governor's order to stop operations. Some 100 local residents, mainly elderly people, gathered outside the site to stop trucks and bulldozers from getting inside the construction area.

Okinawa is a focal point of the U.S. military presence in Asia amid deepening rivalry with China. Local residents are fiercely opposed to the base, as a series of sexual assaults by U.S. troops from the base has sparked violent protests and anger. Many offending soldiers have received either no or very light punishments.

American troops were reportedly involved in over 1,000 sex crimes between 2005 and 2013 in Japan.

The row over the relocation has dragged on for nearly two decades, putting successive Japanese governments between a rock and a hard place as they have struggled to satisfy the U.S. and keep local anger in check at the same time.

Under a 1996 agreement with Washington, the Tokyo government must move the Futenma airbase, which is located in a residential area. Residents say the base should be closed down completely on the island instead of being replaced.

Earlier this month, Okinawa Governor Takeshi Onaga revoked the approval issued by his predecessors for work on the new base, but Tokyo rejected it and said the plan should continue as scheduled.

The U.S. has had a military presence in Japan since the end of World War II. Okinawa hosts about half the roughly 50,000 U.S. troops in Japan, the biggest deployment of American forces outside the home front.