American Airlines has joined Southwest Airlines\n \n (LUV) in suspending alcohol services on flights, the airline said Saturday. The decision follows a recent assault of a Southwest flight attendant that resulted in a serious injury. “Flight attendants are on the front lines every day not only ensuring our customers’ safety, but are also calming fears, answering questions, and enforcing policies like federally-required face masks,” said Brady Byrnes, managing director of flight service at American, in a memo to flight attendants obtained by CNN. “Over the past week we’ve seen some of these stressors create deeply disturbing situations on board aircraft,” the memo said. “Let me be clear: American Airlines will not tolerate assault or mistreatment of our crews.” Like other airlines, American first suspended alcohol sales in March 2020 to minimize interaction between crew and passengers and to ensure safer flights. The airline said services will remain suspended through September 13. The date coincides with the end of the Transportation Security Administration’s mask mandate for all planes. The mandate requires masks on all travelers in airports, airplanes, terminals, trains, buses and boats. It was set to end on May 11 but the TSA extended it to September. American’s extended suspension on alcohol service comes after the airline reinstated beverage services including alcohol on May 1 in all of its domestic premium cabins. The airline says alcohol will continue to be offered in first and business class cabins but only inflight. Alcohol sales were initially slated to resume on the airline’s main cabin on June 1, but will remain paused. “While we appreciate that customers and crewmembers are eager to return to “normal,” we will move cautiously and deliberately when restoring pre-COVID practices,” Byrnes said in the memo. “We also recognize that alcohol can contribute to atypical behavior from customers onboard and we owe it to our crew not to potentially exacerbate what can already be a new and stressful situation for our customers,” Byrnes said. On May 23, a Southwest passenger was arrested on suspicion of felony battery causing serious injury after she allegedly struck a flight attendant during a flight from Sacramento to San Diego, according to a statement from the Port of San Diego Harbor Police Department. The flight attendant suffered facial injuries and lost two teeth, according to Lyn Montgomery, president of the union that represents Southwest’s flight attendants. Following the incident, Southwest made the decision to “re-evaluate the restart of alcohol service on board” and suspended services indefinitely. In a statement, United said Saturday that it is still serving alcohol on flights that are more than two hours long. Similarly, Delta \n \n (DAL)said it is serving beer, wine and cocktails on its flights. Since the beginning of the year, about 2,500 reports of unruly behavior by passengers have been reported, including about 1,900 reports of passengers refusing to comply with the federal face mask mandate, the FAA said in a news release on Monday.