For the U.S. military in Japan, it's a holiday season ritual as regular as decorating the Christmas tree: Every year, senior officers gather at a base on Okinawa and promise to reduce drunken driving among their service members.

2016 was no different. On Dec. 6, leaders from the army, navy, air force and marines gathered at Camp Foster to sign a proclamation against drunken (and drugged) driving.

"I can tell you that although the numbers (of incidents) are down this year, we still will not rest," said Lt. Gen. Larry Nicholson, the top U.S. military officer on Okinawa. "We will continue to work very, very hard because one is too many, and we have an obligation to ourselves and to the citizens of Okinawa to eliminate all cases of drinking and driving."