Nago Mayor Susumu Inamine will lead a delegation of Okinawa residents and politicians to Washington on Thursday, as tensions rise between the mayor and the central government over the plan to build a U.S. military replacement base in the city's Henoko district.

The central government is thinking of bringing the start of construction forward from next spring to this autumn. Inamine told reporters Monday that Nago is still reviewing the Okinawa Defense Bureau's request to use Henoko Bay in the project.

"I can't believe they would progress with construction. It's impossible," Inamine said.