NAHA, OKINAWA, JAPAN - Anger is swirling on the southern Japanese island of Okinawa after an alleged rape by a US Marine, but experts doubt it will lead to serious moves to reduce troops in the strategic US hub.

Despite the furious reaction by Japanese leaders, the government has committed to a US base plan and protests have so far been small in Okinawa, home to half of the more than 40,000 US troops in Japan.

Japanese police last week arrested Staff Sergeant Tyrone Luther Hadnott, 38, after a girl, 14, said he raped her in his car. Hadnott has admitted trying to forcibly kiss her but denied rape.

The latest incident rekindled memories of the gang-rape in 1995 of a 12-year-old girl by three US soldiers, which set off major protests on the island and set in motion a process to reduce the number of US troops there.

But Masaaki Gabe, professor of international politics at Okinawa's Ryukyu University, said that Okinawans would not unite like before.

"Okinawa is now under a political climate different than 1995," Gabe said.

Okinawa was then under left-leaning governor Masahide Ota, a critic of the military presence.

Incumbent Governor Hirokazu Nakaima, an ally of Japan's ruling conservative Liberal Democratic Party, was elected in 2006 over an anti-base rival on promises to improve the island's troubled economy.

The US troops contribute some five percent to the economy of Okinawa, which has one of Japan's highest unemployment rates, and Tokyo awards subsidies to communities willing to host US troops.

"The present governor obviously does not want to worsen the relationship with the central government," Gabe said.

US troops are stationed under a security alliance reached after World War II when Japan became constitutionally pacifist. Okinawa, which was under US control until 1972, is a key base due to its proximity to the Taiwan Strait.

Under a deal finalised in 2006 after protracted negotiations with Tokyo, Washington agreed to shift some 8,000 Marines by 2012 to the US territory of Guam.

But in a move criticised by Okinawan activists, the United States has at the same time installed a Patriot missile defence system on the island amid concern over North Korea, which shot a missile over Japan in 1998. Akira Kato, a professor of political science at Obirin University, said the island had always struggled with balancing opposition to the foreign forces with the positive impact on the economy.

"Unless Okinawa really becomes independent economically, it would be impossible for it to become free of US bases," he said.

He also noted that President George W. Bush's administration, which has spearheaded a realignment of US forces in Japan and across the world to meet new threats, would be out of office in January.

"The incident occurred at a time of political change," he said.

In a controversial part of the 2006 deal, the US military agreed to relocate an air station opposed in the crowded city of Ginowan but only to move it to a small town elsewhere in Okinawa.

Activists accused Governor Nakaima and his allies in Tokyo of dividing the Okinawan public and said they hoped for larger protests in the future.

"The government argues the realignment plan would scale down the US military presence and reduce the strain on Okinawa, but we say it would not reduce the burden but rather strengthen it," said Shiko Sakiyama, chairman of the anti-US base group Okinawa Peace Movement Center.

But he acknowledged: "So long as Nakaima takes a position conciliatory towards US bases and the security alliance, it would be difficult for Okinawa to unite like before."