U.S. Defense Secretary Mark Esper, center, is greeted by U.S. military personnel upon arriving in Kabul, Afghanistan, Sunday, Oct. 20, 2019. Esper arrived Sunday in Afghanistan, where stalled peace talks with the Taliban and persistent violent attacks by the insurgent group and Islamic State militants have complicated the Trump administration’s pledge to withdraw more than 5,000 American troops. He told reporters traveling with him that he believes the U.S. can reduce its force in Afghanistan without hurting the counterterrorism fight against al-Qaida and the Islamic State group. (AP Photo/Lolita C. Balbor)

U.S. Defense Secretary Mark Esper, center, walks Gen. Scott Miller, right, chief of the U.S.-led coalition in Afghanistan, at the U.S. military headquarters in Kabul, Afghanistan, Sunday, Oct. 20, 2019. Esper arrived Sunday in Afghanistan, where stalled peace talks with the Taliban and persistent violent attacks by the insurgent group and Islamic State militants have complicated the Trump administration’s pledge to withdraw more than 5,000 American troops. He told reporters traveling with him that he believes the U.S. can reduce its force in Afghanistan without hurting the counterterrorism fight against al-Qaida and the Islamic State group. (AP Photo/Lolita C. Balbor)

U.S. Defense Secretary Mark Esper, center, arrives in Kabul, Afghanistan, Sunday, Oct. 20, 2019. Esper arrived Sunday in Afghanistan, where stalled peace talks with the Taliban and persistent violent attacks by the insurgent group and Islamic State militants have complicated the Trump administration’s pledge to withdraw more than 5,000 American troops. He told reporters traveling with him that he believes the U.S. can reduce its force in Afghanistan without hurting the counterterrorism fight against al-Qaida and the Islamic State group. (AP Photo/Lolita C. Balbor)