alcohol on and off base, Stars and Stripes reported.
"The vast majority of soldiers, sailors, airmen, marines and civilians in Japan serve honorably and make great contributions to the defense of Japan," USFJ said in a statement.
"When our service members fail to live up to the high standards we set for them, it damages the bonds between bases and local communities and makes it harder for us to accomplish our mission. We are committed to being good neighbors with our host communities and we are thankful for the support we receive from them every day."
USFJ has also instructed all commanders across Japan to "immediately lead mandatory training to address responsible alcohol use, risk management and acceptable behaviour."
This was mandatory to all military members and U.S. government civilians in Japan.
Service members on mainland Japan reacted to the ban.
"Drinking is a regular part of my off-duty life, so that's going to change my weekend plans," said Staff Sgt. Ian Rose, according to Stars and Stripes. "I guess I'll have to figure out something else to do."
Petty Officer 2nd Class Brittany Buhmman, added, "We're in a gorgeous country that people need to take some time and experience sober. If liberty isn't restricted, there are so many things [service members] can go out and do."