After graduation, Jeffers joined the United States Army in 1996, serving as an operations officer and rifle platoon leader in the
10th Mountain Division light infantry, stationed at
Fort Drum, New York. He later transferred to the
75th Ranger Regiment and served as a rifle platoon leader. He was then transferred to
Fort Lewis, where served as Air Operations Officer and company commander of 1st Battalion, 5th Infantry Regiment, 1st Brigade, 25th Infantry Division. In April 2003, he served as Air Operations Officer and was a company commander with 2nd Ranger Battalion of the
75th Ranger Regiment where he deployed to Iraq to conduct combat operations
2003 invasion of Iraq. He was later deployed to
Afghanistan, serving in
Operation Enduring Freedom, the 2001–2014 campaign of American military actions in Afghanistan. Jeffers graduated from the
United States Army Command and General Staff College in 2007, and was promoted to the rank of lieutenant colonel. He was assigned to the
US Army Special Operations Command at
Fort Bragg, North Carolina. He attended a counterterrorism and public policy fellowship program at
Duke University from 2015 to 2016, after which he was assigned to the
Joint Forces Command, leading the 1st and 2nd brigades of the
7th Infantry Division. About a year later, he was transferred to Afghanistan, where he became an advisor to the commander of
Operation Resolute Support, the country's
NATO military mission. Jeffers led a brigade under the
Army Special Operations Command during
Operation Inherent Resolve, the United States military operation against the
Islamic State. He became a part of the
Joint Staff as a deputy director for counterrorism and special operation. In June 2024, he was appointed as the commander of the
Special Operations Command Central at
MacDill Air Force Base. In November 2024, Jeffers traveled to
Beirut to take up his appointment as the co-chair of the "implementation and monitoring mechanism" for the
2024 Israel–Lebanon ceasefire agreement, following the
2024 Israeli invasion of Lebanon. In January 2026, the
Second Trump Administration appointed Jeffers as the commander of the
International Stabilization Force, a
United Nations-mandated peacekeeping force overseeing security operations in the
Gaza Strip as part of the
2025 peace plan to end the
Gaza war, a multiyear conflict between
Israel and the Palestinian militant and political organization
Hamas which resulted in the Israeli military occupation of much of the strip. ==References==