NAHA, Japan (Kyodo) -- A U.S. Air Force member stationed in Okinawa Prefecture was sentenced to five years in prison on Friday for kidnapping and sexually assaulting a girl under the age of 16 in December last year, with the court rejecting his not guilty plea.

In handing down the ruling on Brennon Washington, 25, Naha District Court Presiding Judge Tetsuro Sato said the airman stationed at Kadena Air Base continued performing sexual acts on the victim even after he was aware there was no consent.

Sato called Washington's action "malicious" and one that "disregarded the girl's decision-making in exercising sexual freedom."

The case not only triggered fresh anti-base sentiment in the prefecture, which hosts the bulk of U.S. military facilities in Japan, but also drew attention as local police and the central government did not disclose the incident to the prefectural government.

It was only in June this year, three months after his indictment, that the case came to light through a local media report, sparking protests from the prefectural government.

The following month, the central government reviewed its information-sharing arrangements with local governments and vowed to notify them of any crimes allegedly committed by U.S. military members.

Following the ruling, Brig. Gen. Nicholas Evans, commander of the 18th Wing at Kadena Air Base, said he is "deeply troubled" by the incident and vowed to cooperate with local authorities to ensure the individual completes the sentence mandated by the local court.

Okinawa Gov. Denny Tamaki said in a statement, "We cannot tolerate incidents that ignore the dignity of women."

According to the ruling, Washington asked the girl to speak with him in his car at a park in the village of Yomitan on Dec. 24 last year. He then drove her to his off-base residence before sexually assaulting her despite knowing she was under 16.

Under Japanese law, sexual intercourse with a person under 16 is illegal regardless of consent, with an exception made for cases in which an individual aged 13 to 15 has consensual intercourse with a person less than five years older than them.

In the trial, the girl stated that she told him her age and that she said "stop" in English when he sexually assaulted her.

Sato said there was "nothing unnatural" about the girl's testimony, describing it as "consistent with the facts and credible."

Prosecutors sought a seven-year jail term for Washington.

Okinawa continues to bear a heavy load as host to many U.S. military facilities more than half a century after its 1972 reversion from U.S. control following Japan's defeat in World War II. Crimes committed by U.S. service members and nonmilitary personnel have been a constant source of grievance for locals.