There's good news this month from the Centers for Disease Control and Prevention: In 2015, the smoking rate among adults in the United States fell to a new low of 15 percent. Within the military, though, smoking rates remain substantially higher. This not only harms the health of soldiers but also impairs military performance, which is why Secretary of Defense Ashton Carter should push to further discourage smoking.

According to a 2011 Defense Department survey, 49 percent of service members used some form of nicotine product within the previous year. Within the U.S. Marine Corps, the share was 60 percent. Those who reported being current smokers accounted for 24 percent of all military personnel.

The rates vary substantially by service (smoking is almost twice as common in the marines as in the air force) and by pay grade (with the most senior officers smoking at one-tenth the rate of the most junior enlisted personnel). Some of this variation is to be expected; smoking is also much lower among civilians in high-income households with high levels of education. Even adjusting for education and income, though, smoking is noticeably higher overall in the military.