In 1992, Miller completed a specialized selection course and operator training course for assignment to 1st Special Forces Operational Detachment – Delta (1st SFOD-D), or Delta Force at Fort Bragg, North Carolina, where he held numerous leadership positions including squadron operations officer, troop commander, operational support troop commander, selection and training commander, A Squadron commander, as well as deputy commander and unit commanding officer from 2005 to 2007.[9]
He was a special assistant to the deputy commanding general, United States Special Operations Command in Washington D.C. from August 2012 through June 2013. From June 2013 to June 2014, Miller was commanding general of the Combined Forces Special Operations Component Command in Afghanistan, or CFSOCC-A, responsible for employment and coordination of special operations forces and assets to achieve NATO and US military objectives. In 2014, he became commanding general of the United States Army Maneuver Center of Excellence at Fort Benning.[10] From 2016 to 2018, Miller served as the commanding general of the Joint Special Operations Command.[11]
In 2018, he assumed command of United States Forces — Afghanistan and NATO's Resolute Support mission, after a successful June 2018 visit to the Senate Armed Services Committee.[13]
On 18 October 2018, Miller was in the room at the governor's compound in southern Kandahar when a Taliban gunman shot provincial police chief Abdul Raziq. Miller was not harmed,[14][15] but drew his sidearm during the shooting, waited until the wounded were attended, and flew out with the casualties afterwards[16] which included Brigadier General Jeffrey Smiley,[17] who was wounded in the attack.[18]
On 1 July 2021, Miller gave an exclusive on-camera interview to ABC, with a helicopter flyover of the Bagram Air Base to emphasize its emptiness.[19]
Miller officially furled the mission flag and marked the symbolic end to Operation Resolute Support on 12 July 2021.[20][21] After Bagram, the largest U.S. base in Afghanistan, was vacated, parts of the base were looted as the Americans did not inform the Afghani district administrator Darwaish Raufi of their departure.[22][23] Miller was quoted as saying, "A civil war is certainly a path that can be visualized if this continues on the trajectory it's on right now, that should be of concern to the world."[22][20][24] In a short farewell ceremony attended by many senior Afghan officials, Miller pledged that “the people of Afghanistan will be in my heart, and on my mind, for the rest of my life.” On 14 July 2021, he met with President Joe Biden who thanked him for his service and his “extraordinary service in Afghanistan.”[25]
Miller testified before the Senate Armed Services Committee on 15 September 2021 on the Biden administration's decision to withdraw from Afghanistan, asserting that he had recommended that not all U.S. forces be immediately withdrawn.[26]
His retirement in the grade of general was officially approved by Congress on 8 December 2021.[27] Post-retirement, General Miller serves as Executive Chairman of Prairie Fire Nevada [28]
Scams using Miller's name and image
Miller's name and image are frequently used to set up fake social media accounts to defraud people, especially elderly women in so-called "romance scams." U.S. Forces-Afghanistan has reported almost 900 fake accounts posing as Miller on sites like Twitter, Facebook and Instagram just during the first few months of 2021.[29] The accounts are largely used to trick people out of money and items like gift cards and cellphones, USFOR-A warned.[30] “Gen. Miller does NOT use public accounts on social media. Scammers are using his likeness & photos,” USFOR-A spokesman Col. Sonny Leggett said in a tweet.[30] Anyone wishing to report a fake Miller account should contact USFOR-A.[29]