This April 26, 2010, photo shows a U.S. Marines CH-46E helicopter taking off from the U.S. Marine Corps Air Station Futenma in Ginowan, Okinawaprefecture. Okinawan officials on Dec. 27, 2013, approved the long-stalled relocation of the controversial U.S. military base, a breakthrough that would remove a decades-long source of friction between Tokyo and Washington. (Toshifumi Kitamura/AFP/Getty Images)

Japan won local approval Friday to begin the relocation of a controversial U.S. Marine base on the island of Okinawa, a move that officials in Washington hailed as a major diplomatic breakthrough.

Okinawa Gov. Hirokazu Nakaima signed off Friday morning on plans for landfill work that will allow the Futenma Air Station to be moved to a less-populated area, according to Japan’s Kyodo News agency. A formal announcement was expected later in the day.

Nakaima’s approval is significant because it breaks a seven-year stalemate in which the relocation plan — agreed upon by Tokyo and Washington — was held up by local opposition. Prime Minister Shinzo Abe persuaded Nakaima to accept the relocation by offering a major spending package aimed at infrastructure and development projects on the island.

The relocation of Marine Corps Air Station Futenma is a key piece of a broader U.S. realignment of troops and re­sources in the Asia-Pacific region. The Obama administration is seeking to augment its presence in the region to counterbalance China’s military rise and anticipate threats from a volatile North Korea.

“Reaching this milestone is a clear demonstration to the region that the alliance is capable of handling complex, difficult problems in order to deal effectively with 21st century security challenges,” U.S. Secretary of Defense Chuck Hagel said in a statement, referring to the relationship the United States and Japan forged after War World II.

Completion of the new air station, which is expected to include two runways more than a mile long each, will take approximately a decade, U.S. officials said. As the new facility is built, the Pentagon expects to reduce the number of Marines based on Okinawa from 18,000 to roughly 10,000, as more are deployed to Guam, a U.S. territory, Australia and Hawaii.

U.S. officials have pressed Japanese leaders for years to pave the way for the construction of a new base along the rural northern coastline. The Futenma base currently sits in the middle of dense Ginowan city, surrounded by schools and homes. Residents say the base poses safety concerns, citing a 2004 incident in which a U.S. helicopter clipped a university administration building. Some also complain about noise pollution and about the sometimes unruly behavior of U.S. troops in Japan. Washington and Tokyo have been trying for nearly two decades to move the Futenma base.

Most Okinawa residents are opposed to a new U.S. military facility on an island that already hosts 34 of them. Okinawa comprises less than 1 percent of Japan’s total land area but hosts half of the 50,000 U.S. troops stationed in Japan. In 2009, then-Prime Minister Yukio Hatoyama pledged to move Futenma off Okinawa, citing the prefecture’s disproportionate burden. His move failed, but in the process it hardened opposition to the relocation.

Until Hatoyama’s pledge, Nakaima, the governor since 2006, was on board with the relocation plan. But he faced increasing pressure to stop the move, and for several years he said publicly he would never allow it. Still, some officials in Tokyo believed that Nakaima was a pragmatist willing to negotiate.

“He was just looking for the right bargain, and that’s what he got,” said Patrick Cronin, senior director of the Asia-Pacific Security Program at the Center for a New American Security.

Even with Nakaima’s approval, the relocation of the Futenma is precarious, and it could be delayed or derailed by mass protests or court challenges. Some analysts say airplane crashes or crimes by U.S. service members could also change the political atmosphere.

Following the approval, roughly 2,000 protesters flocked to the Okinawan prefectural assembly building in Naha, local media reported. They held signs saying, “Leave office, Governor” and “We won’t allow the landfill.”

Harlan reported from Seoul. Yuki Oda, in Tokyo, contributed to this report.