A statement released by U.S. Forces Japan says the 11 p.m. to 5 a.m. curfew will apply to U.S. military personnel whether they are stationed in Japan or just visiting. It requires them to be in their homes, on base or wherever they are lodging.
Lt. Gen. Salvatore Angelella said U.S. military members in Japan also will have to take "core values training." The military's liberty policy is also under review.
Japan's defense minister, Satoshi Morimoto, told reporters earlier Friday that he was instructed by Prime Minister Yoshihiko Noda, "to fully discuss the matter with the U.S. side and come up with measures to eradicate the problem so that crimes like this are never repeated again."
The two sailors were in Okinawa on a brief stopover and are now in Japanese custody. According to Japanese media, they had been drinking before they attacked the woman, in her 20s, who was on her way home before dawn Tuesday.
"I want to personally apologize for the grief and trauma the victim has endured and the anger it has caused among the people of Okinawa," Angelella told reporters.
Angelella said American military personnel are "held to a higher standard."
Both he and U.S. Ambassador to Japan John V. Roos said the U.S. will cooperate in the Okinawan police investigation. Roos said the U.S. government viewed the situation with "utmost seriousness."
"We will put forward every effort to make sure that incidents like this do not happen," Roos said.
The Naval Criminal Investigative Service has begun its own investigation, although Japan has primary jurisdiction.
Seaman Christopher Browning of Athens, Texas, and Petty Officer 3rd Class Skyler Dozierwalker of Muskogee, Okla., were arrested Tuesday. Both are 23, joined the military in 2008 and are assigned to Joint Naval Air Station, Fort Worth, Texas.
The latest case has inflamed chronic tensions between the U.S. military and Okinawa over base-related crimes and other issues. Okinawans also have been protesting plans to deploy the Marine Corps' MV-22 Osprey to a base there because of safety concerns.
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. That outcry eventually led to an agreement to close a major Marine airfield, but that plan has stalled for more than a decade over where a replacement facility should be located.