American sailors across Japan were confined to their bases and banned from drinking alcohol starting Monday as the U.S. Navy responded to a drunken-driving case that stoked anger nationwide.

The largely open-ended order applies to all sailors based in or transiting through Japan. Commanders are additionally urging civilian contractors and family members to observe it voluntarily.

The DUI case in Okinawa Prefecture was the latest in a spate of incidents there that have strained relations.

“We have recognized a problem, we’re owning it, and we’re doing everything we can to ensure that every one of our sailors understands how important our behavior is to the alliance and to our relationship to the people of Japan,” said Cmdr. Ronald Flanders, spokesman for U.S. Naval Forces Japan.

All sailors are confined to their bases unless they are billeted to in-town accommodations.

Those who live off base will be allowed to travel to and from work, schools, gas stations, grocery stores and gyms. Other activities are prohibited by the order and subject to military law.

Flanders said the liberty restriction will remain in place until all personnel have received new training from their unit commanders. He said this training will stress standards of behavior while off-duty and intervening before incidents like the drunken-driving case occur.

As for the alcohol ban, that is indefinite.

“There is no timetable in place,” Flanders said. “The alcohol restriction will remain in effect until the commander of the 7th Fleet and the commander of Naval Forces Japan determine that all personnel have fully embraced their responsibilities of being a U.S. ambassador at all times.”

On Saturday, Petty Officer 2nd Class Aimee Mejia, who is assigned to Kadena Air Base in Okinawa, was arrested after allegedly driving a car on the wrong side of the road, hitting two cars and injuring two people.

Mejia is being held by Japanese police on suspicion of drunken driving. Kyodo News said Monday her case would be referred to prosecutors the same day.

The incident occurred during what the U.S. military dubbed a period of unity and mourning in Okinawa after the body of a 20-year-old Japanese woman was found on a roadside in the prefecture. An American contractor employed at Kadena has been arrested in that case.

In March, a sailor was arrested following the suspected rape of a Japanese tourist at a hotel in Okinawa. He has since pleaded guilty.

And in 1995, the rape of a schoolgirl by three U.S. servicemen sparked widespread protests in Okinawa.

Commanders say incidents of off-base misconduct have fallen since the introduction of restrictions in 2013 that include requiring individuals of some ranks to be accompanied by a designated companion while spending an evening on the town.

According to Gunnery Sgt. Tiffany Carter, a spokeswoman for U.S. Forces Japan, 2014 saw the lowest level of cases involving U.S. troops since 1972, when Okinawa was handed back to Japan.

“The policy gives component commanders the discretion to apply additional measures they deem necessary to address specific infractions or trends,” Carter said.

“We deeply regret this incident,” she said about the latest case. It was “especially hurtful and regrettable because it occurred during the period of unity and mourning.”

Some observers expected a flare-up of anti-American protests following the woman’s death in May. Commanders imposed a midnight curfew and no-drinking order off bases in Okinawa for 30 days from May 28.

The naval restrictions are considerably more stringent and are in effect nationwide.

While military orders such as this are unenforceable against off-duty civilian hires and troops’ family members, commanders urged them to observe it.

“All Americans associated with the U.S. Navy are under increased scrutiny right now,” Flanders said. “So we are asking that our civilian workforce, our contractors and our families understand the gravity of the situation and comply with the spirit of the order.”

No-alcohol bans are routinely in place in active war zones. Nonalcoholic beer was the only tipple available for many troops deployed to Iraq and Afghanistan except for liquor smuggled onto base or obtained from the troops of NATO nations that permitted booze.

In 2012, a U.S. soldier shot and killed 16 Afghans after drinking. He was sentenced to life without parole.