The U.S. Army is reportedly treating two active-duty soldiers for vaping-related lung ailments, officials announced on Wednesday. Earlier this month, most of the military banned e-cigarette sales at base exchanges, The Wall Street Journal reports. Vaping-related illnesses have affected more than 1,000 people nationwide and been linked to at least 23 deaths in the U.S. In most cases, they have been related to vaping products containing THC. Marijuana use is banned by service members, but it is not yet clear which substances were involved in the two cases.