U.S. military leaders in Japan are clamping down on troops' liberty, curfews and alcohol use ahead of the Memorial Day holiday after a sailor and a Marine veteran were charged with crimes on Okinawa.

All Okinawa-based service members will face off-base restrictions during a monthlong "period of unity and mourning," the commander of U.S. troops in Okinawa announced Thursday.

The new rules go into effect Friday and last until June 24, according to a message from Marine Lt. Gen. Lawrence Nicholson, the head of III Marine Expeditionary Force.

All local clubs and bars will be off limits. Troops who live on base will not be allowed to drink alcohol when they're off base. And those who live off base will be permitted to drink only while in their homes or on base.

All troops must be back in their residences by midnight. And off-base celebrations or hotel-room parties are now banned.

Troops are still allowed to eat at local restaurants, but they may not drink alcohol with their meals. Any vehicles that enter or leave military installations between midnight and 5 a.m. will be subject to sobriety checks.

"These measures are not intended as punishment," Nicholson wrote . "Rather, I seek to reaffirm our responsibilities as residents of Okinawa while demonstrating our deepest sympathies for the victims and their families."

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In an email obtained by Military Times, a senior enlisted Marine told his troops it could easily become a punishment if service members don't take the situation seriously.

"We are showing solidarity with the Okinawan people as they go through this period of mourning," the Marine wrote. "However, if we experience a bunch of jackassery out in town, this could quickly change to a punishment, and all need to understand that and take personal responsibility."

The new restrictions follow two high-profile crimes on Okinawa.

Kenneth Franklin Gadson, a Marine veteran who was working at Kadena Air Base as a civilian, is accused of murdering 20-year-old Rina Shimabukuro and dumping her body, according to Stars and Stripes . The incident comes little more than two months after Justin Castellanos, a sailor assigned to Camp Schwab, was arrested for allegedly raping a Japanese woman.

Policemen escort US citizen and former US Marine Kenneth Franklin Shinzato (C) to the prosecutor's office at Uruma Police Station in Uruma, Okinawa prefecture, on May 21, 2016. US citizen and former US Marine Kenneth Franklin Shinzato, who works at the US Kadena Air Base, has reportedly admitted to raping and killing 20-year-old Rina Shimabukuro, who had been missing since late April. / AFP / JIJI PRESS / JIJI PRESS / Japan OUT (Photo credit should read JIJI PRESS/AFP/Getty Images)

Japanese policemen escort Kenneth Franklin Shinzato, a military contractor, to the prosecutor's office in Okinawa on May 21. The Marine vet, who works at the U.S. Kadena Air Base, has reportedly admitted to raping and killing 20-year-old Rina Shimabukuro, who had been missing since late April.

Photo Credit: JiJi Press/AFP/Getty Images

"This behavior adversely affects not only the victims of crime, but also the relationship we maintain with our Okinawan neighbors and the important bilateral relationship we share with the government of Japan," Nicholson wrote .

Liberty rules in Japan are reviewed regularly. In 2014, military leaders there loosened the rules, and troops were allowed to stay out later without a liberty buddy. Two years prior, the liberty requirements had been restricted following a series of crimes, including the rape of an Okinawan woman by a pair of U.S. sailors.

American civilians in Okinawa on official U.S. business or working as government contractors are also "highly encouraged" to abide by the new rules, according to Nicholson's memo .