Two U.S. Navy petty officers are in custody in Okinawa in the alleged sexual assault and robbery of a Japanese woman in an incident that could further inflame anti-American sentiment on the strategic Japanese island.

The two sailors followed a 27-year-old woman to her apartment complex where they allegedly raped and robbed her in the parking lot about 4 a.m. Tuesday, authorities in Japan said.  A third sailor who reportedly witnessed the assault was taken into custody by Japanese police and later released to the U.S. Navy, according to NBC News.

The sailors were identified as Seaman Christopher Browning and Petty Officer 3rd Class Skyler Dozierwalker, both 23, of the Fort Worth Naval Air Station in Texas, The Associated Press reported.

According to Japan broadcaster NHK World, the woman told police that she was walking home when she was attacked. She said she did not know the men. She suffered a neck injury.

Under the terms of a Status of Forces Agreement between the U.S. and Japan, Japanese authorities have jurisdiction and the authority to charge and bring the accused to trial. If convicted, the men could also be imprisoned by the Japanese.

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The Naval Criminal Investigative Service, or NCIS, is conducting a parallel investigation alongside the Japanese in the event the two accused are released to U.S. Navy custody.

The two sailors in custody were on overnight leave and crewmembers on a U.S. Navy cargo plane that was in Okinawa for only a day or two while on a delivery mission, officials told NBC News.

Okinawa prefecture spokesman Susumu Matayoshi said the alleged rape “shocked all Okinawans and is unforgivable,” the AP reported.

Vice Foreign Minister Shuji Kira lodged a protest with U.S. Ambassador John Roos, who promised full cooperation with the investigation, according to the AP.

Okinawa hosts more than half of the nearly 50,000 American troops in Japan. Local opposition to the U.S. bases over noise, safety concerns and crime flared into mass protests after the 1995 rape of a schoolgirl by three American servicemen.

Many Japanese want to see the U.S. airbase moved off the island chain.

NBC News' Jim Miklaszewski contributed to this report.

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