The U.S. is planning to send almost 4,000 additional troops to Afghanistan, according to a Trump administration official. Defense Secretary James Mattis could announce the deployment—the largest so far under President Donald Trump—as early as next week. The military’s top commander in Afghanistan has said he needs more forces to fight a reinvigorated Taliban insurgency and the growing threat of ISIS in the country. The additional troops will train and advise Afghan forces and participate in counterterror operations. The war, now in its 16th year, has claimed the lives of close to 2,400 American service members, including three killed in a Taliban attack this past weekend.