(VOVworld) - Japan's government started offshore construction work Monday on relocating a US Marine base on Okinawa. The step marks the beginning of the main construction to move Marine Corps Air Station Futenma to Henoko, a less populated area on the island's east coast.

A boat goes by cranes being used for the preparation work to relocate the U.S. Marine base to Henoko (Photo: AP)

The move came just days after US Defense Secretary James Mattis reaffirmed with Japanese leaders that the Henoko plan is the only option. The US base has existed on Okinawa for decades.