Land reclamation work begins in the Henoko district of Nago on Dec. 14 with the dumping of dirt and sand into waters marked off by an embankment even as water-borne protesters oppose the move. (Video footage by Jun Kaneko and Kengo Hiyoshi)

Bulldozers on Dec. 14 pushed the first loads of dirt and sand into the waters off the Henoko district of Nago, Okinawa Prefecture, marking an irreversible step in the contentious relocation of a U.S. military base.

The start comes despite heated opposition by the Okinawa people to moving U.S. Marine Corps Air Station Futenma from Ginowan, also in Okinawa, to the Henoko area.

After Okinawa Defense Bureau officials notified prefectural government officials that the dumping of dirt and sand would commence, Okinawa Governor Denny Tamaki met with reporters in Naha.

"I cannot but hold sharp anger at the dumping of dirt and sand without listening to any of the requests made by the Okinawa prefectural government," Tamaki said. "Such an act will only bring about strong opposition from the Okinawa people, and the central government should recognize that the more they decide to push ahead with the project, the greater will be the anger of the people."

About 300 protesters gathered in front of a gate entrance to Camp Schwab by about 9 a.m. on Dec. 14. One of those expressing their opposition to the land reclamation work was Mikiko Onaga, the widow of the late Okinawa Governor Takeshi Onaga, who died in August from pancreatic cancer.

Another 20 protesters paddled their kayaks out near the land reclamation site to protest the start of the dumping of dirt and sand.

Meanwhile, in Tokyo, Defense Minister Takeshi Iwaya indicated that even with the start of dirt dumping, the government still faced a tough course in completing the relocation so the Futenma land could be returned to Japan.

He said the land could be returned as early as fiscal 2022, but added, "It is a fact that achieving that goal has now reached a very difficult stage."

Reclamation work in the Henoko waters will permanently alter the ecological environment into which the fill material is being dumped.

The work on Dec. 14 was concentrated on an approximately 6.3-hectare area surrounded by embankments on the southern side of Camp Schwab. That area represents about 4 percent of the total waters that will eventually be reclaimed to construct a V-shaped runway at the Marine base.

The project is being overseen by the Defense Ministry's Okinawa Defense Bureau.

Dump trucks were used to transport the dirt and sand that had been unloaded from barges anchored along an embankment on the northern side of Camp Schwab. The barges transported the dirt and sand from a ship that had used a private-sector pier in another section of Nago. Bulldozers along the southern side of Camp Schwab then shoveled the fill material into the waters.

Under the government's plan, about 160 hectares of water will be reclaimed using 20.62 million cubic meters of dirt and sand. After the reclamation work is completed, a new base totaling about 205 hectares will be constructed, which will include some parts of Camp Schwab now on land.

Japan and the United States agreed in 1996 to relocate the Futenma base and return the land to Japan. That agreement came in the wake of huge public outrage at the rape of an Okinawa schoolgirl by three U.S. servicemen.

Henoko eventually became the planned site, but public opposition in Okinawa remained strong to the move. In addition to Tamaki, who was elected in September on a platform opposed to the Henoko move, his predecessor, Onaga, was also elected on a campaign opposed to the Henoko move.

However, Japan and the United States have long insisted that Henoko was the only solution for moving the Futenma base.

The central government apparently proceeded with the reclamation work before other opportunities arose for the Okinawa public to voice opposition to the move.

The Okinawa prefectural government is planning to hold a referendum on Feb. 24 about the Futenma move. Local elections are also expected for the spring along with a by-election in the Lower House Okinawa No. 3 district that was vacated when Tamaki ran for governor.

(Shinichi Fujiwara contributed to this article.)