The Naha branch of the Fukuoka High Court ruled Friday that Okinawa Gov. Takeshi Onaga’s cancellation of a landfill project related to construction of a replacement facility for U.S. Marine Corps Air Station Futenma was illegal.

The decision hands the central government, which is pushing for completion of the project in the Henoko district, a victory in the nearly two-decade standoff between Okinawa and Tokyo over the issue.

The legal struggle is likely to continue however, as lawyers for Okinawa said following the verdict they will appeal to the Supreme Court. If the top court agrees to hear the case, a final decision could be handed down as early as next spring.

In addition, land reclamation work at Henoko, suspended after a settlement was reached between the prefecture and the central government in March, is not likely to be restarted anytime soon.

In his ruling, high court Judge Toshiro Tamiya said Onaga’s refusal to withdraw an order, originally made last year, canceling permission for the Henoko-related landfill project was illegal. The judge also ruled former Gov. Hirokazu Nakaima’s decision to grant permission for the landfill was legal, and within his rights as governor.

“Even taking into account the desire of Okinawans who seek reductions in the base facilities and see the reclamation as unprofitable, there is nothing lacking in the requirements for approval (of the landfill project),” the ruling said. “There’s nothing illegal about the previous governor’s approval and because of that, cancellation of it cannot be upheld.”

Last summer, a committee of legal experts appointed by Onaga issued a report that found legal flaws, especially related to the environmental impact assessment, in Nakaima’s approval. The report was used by Onaga, who defeated Nakaima in the 2014 gubernatorial election, as the basis for his decision last October to withdraw permission for the landfill work.

The central government retaliated in November, when the Land, Infrastructure, Transport and Tourism Ministry, which has jurisdiction over laws that cover landfill projects, sued the prefecture, claiming there were no legal flaws. The Okinawa Prefectural Government countersued the central government in December, seeking to halt the landfill work.

In March, a settlement was reached in which the central government agreed to suspend construction at Henoko and drop its lawsuit against Okinawa. In return, Okinawa agreed to drop its lawsuit, and both sides pledged to work together to seek a solution.

Earlier, when the initial settlement had been proposed, the central government was warned there no guarantees the court would rule in its favor if lawsuits related to frequent changes in construction work were to emerge in the future.

In June, a separate investigation by a third-party panel formed under the direction of the internal affairs ministry said it could not judge the legality of the central government’s order to Onaga to withdraw his cancellation of the landfill approval.

That same month, Onaga said he would not file a fresh lawsuit against Tokyo over the Henoko issue, saying he wanted to resolve the problem through talks. He called on Prime Minister Shinzo Abe to engage in direct talks.

But in July, after the Upper House election in which Abe’s Liberal Democratic Party scored a major victory, the central government decided to file a fresh suit against Okinawa, resulting in Friday’s decision.

Last month, during court proceedings, Onaga said he would comply with the court’s final ruling. However, he added that if the prefecture lost its case, he would still continue to make all possible efforts as governor to prevent relocation of Futenma within Okinawa.

Other measures Onaga could take include refusing to approve any changes in the construction plan, all of which have to be submitted and approved by the governor. That option would create more bureaucratic and possibly legal problems for completing the Henoko project.

“Appealing to the Supreme Court isn’t going to solve the issue. There are various steps that can be taken with regard to Henoko and the surrounding areas. Okinawa and Nago have various ways they can use their local authority over the project,” said Upper House member Yoichi Iha, who represents Okinawa, following the verdict.

Hiroshi Ashitomi, leader of one of the most prominent organizations challenging the expansion and relocation of U.S. military bases, the Anti-Helicopter Base Council, said Okinawa’s fight will continue.

“This judicial ruling does not contribute to the development of local autonomy. People in Okinawa who oppose the expansion of U.S. military bases are put down with brute force by riot police. We will continue to fight, with the power of democracy and freedom,” he said.