TOKYO (Reuters) - The United States military plans to return some land in Okinawa to the Japanese government by the end of the year, the largest transfer since 1972, U.S. Defense Secretary Ash Carter said on Tuesday.

Resentment over the U.S. military presence surged this year after an American civilian working at a U.S. base, Kenneth Franklin, was arrested over the murder of a 20-year-old Japanese woman, Rina Shimabukuro.

Carter made the announcement during a meeting with Japanese Prime Minister Shinzo Abe in the capital, Tokyo.

A senior U.S. defense official said the United States plans to return nearly 10,000 acres (4,000 hectares) of land in northern Okinawa, with a formal ceremony for the return set for Dec. 21 and 22.

“It will be a positive development for the alliance, demonstrating the commitment of both governments to the realignment of U.S. forces,” said the official, speaking on condition of anonymity.

It was the first announcement of a specific timeline for the transfer, which the U.S. military had said in July it was preparing for.

Okinawa, which was under U.S. occupation until 1972, hosts the bulk of the approximately 50,000 U.S. military personnel in Japan.

Although agreed in 1996, the return of the land was delayed by protesters blocking the construction of helipads. The Japanese government recently resumed work at the site.

Carter is in Japan to try to sooth anxieties caused by the victory of President-elect Donald Trump, who has called for allies to pay more to sustain U.S. forces, or face their possible withdrawal.