More than 17 years after the two allies agreed to move the US Marines' Futenma Air Station from a densely populated urban area, the local government has finally consented to a landfill that will enable new facilities to be built on the coast.
The agreement will burnish the credentials of Prime Minister Shinzo Abe in the US, possibly taking some of the sting out of American criticism of his provocative visit Thursday to a war shrine seen by China and Korea as a symbol of Japanese militarism.
The issue has been deadlocked for years, with huge opposition to the new base site among Okinawans who are fed up playing host to an outsized share of the US military presence in Japan, and who want it moved off the island altogether.
Okinawa's scrappy governor Hirokazu Nakaima, long a thorn in the central government's side, this week met Abe, who pledged a big cash injection into the island's economy every year until 2021.
When he came out of the meeting and declared himself impressed with the package on offer, which includes the shuttering of Futenma within five years, he swung behind the move and gave it his blessing.
The governor announced his decision on Friday afternoon on Okinawa where it was met by an angry popular reaction.
Thousands of protesters surrounded the Okinawa local government office, media reports said, with footage showing demonstrators holding banners reading: "Never bend".
Several hundred had stormed the lobby of the building and were staging a sit-in protest, a government spokeswoman said.
Local bureaucrats signed a document early Friday, which gives the governor's green light to landfill in the Henoko area, near another US base, Camp Schwab.
Environmentalists say any development risks seriously damaging the coral reefs in the area as well as the delicate habitat of the dugong, a rare sea mammal.
Nakaima had been a bitter critic of the central government, which he says is unsympathetic to the southern tropical island and still treats it as an "unsinkable aircraft carrier" of the US military, more than 40 years after it was handed back to Japan.
But at Wednesday's meeting, the carrot of Abe's stimulus pledge -- at least 300 billion yen ($2.9 billion) every year until fiscal 2021 -- proved persuasive for the governor of Japan's poorest prefecture.
The US agreed to shut Futenma in 1996 partly in response to soaring anti-base feeling after the gang-rape the year earlier of a 12-year-old girl by three servicemen.
Its position in the middle of a built-up area also makes it less than ideal for the frequent flights by military aircraft.
However, resistance on the islands to a new site left the base in limbo, with Washington's hopes for a resolution regularly frustrated by weak government in Tokyo.
Relations between the two capitals dropped precipitously after the 2009 election of Yukio Hatoyama as prime minister, partly on a platform that he would turf the base out of Okinawa, much to the irritation of Washington policymakers.
His subsequent flip-flop left Okinawans furious and feeling betrayed, and cast a further cloud over the issue.
The deal Abe appears to have struck marks a significant achievement, and one that is expected to smooth relations after years of frustration.
Observers have pointed to the timing and Abe's controversial visit Thursday to the Yasukuni war shrine, seen as a symbol in northeast Asia of 20th century Japan's brutal imperialism, and said his negotiating methods owed more to his fondness for splurging money.
"Abe flashed big cash around to get the nod from the governor, which saved him some face in Washington," said Tetsuro Kato, professor emeritus at Tokyo's Hitotsubashi University.
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