The aircraft carrier USS Nimitz (CVN 68) steams in the Indian Ocean, Jan. 6, 2021. (Mass Communication Specialist Seaman Drace Wilson/Navy)
Army Spcs. Timothy Martin, left, and Shane Flores, middle, and Cpl. Dario Martinez prepare for a detonation during training in Boise, Idaho, Nov. 18, 2020. (Thomas Alvarez/Army)
Six airmen assigned to the 31st Medical Group receive the first Moderna COVID-19 vaccines at Aviano Air Base, Italy, Jan. 8, 2021. (Staff Sgt. K. Tucker Owen/Air Force)
A U.S. Marine Corps F-35B Lightning II approaches a U.S. Air Force KC-135 Stratotanker for an in-air refueling mission supporting Operation Octave Quartz with armed over-watch in Africa, Jan. 1, 2020. (Master Sgt. Joey Swafford/Air Force)
A U.S. Space Force trainee participates on the over-and-under bars obstacle during Basic Expeditionary Airman Skills Training at Joint Base San Antonio-Chapman Annex, Texas, Dec. 2, 2020. This trainee was among the first to attend basic military training before entering the operational Space Force, which was established as the sixth military branch, Dec. 20, 2019. (Staff Sgt. James R. Crow/Air Force)
The statue of the Lone Sailor stands on the snow-covered grounds of Recruit Training Command at Great Lakes, Ill., on Dec. 30, 2020. (MC1 Spencer Fling/Navy)
A U.S. Marine patrols during a force-on-force exercise at Camp Gonsalves, Okinawa, Japan on Oct. 16, 2020. (Lance Cpl. Kolby Leger/Marine Corps)
A UH-60 Black Hawk helicopter, operated by soldiers with Alpha Company, 2-104th General Support Aviation Battalion, 28th Expeditionary Combat Aviation Brigade, flies over the 28th ECAB's area of operations in the Middle East. (Sgt. Andrew Johnson/Army)
U.S. sailors inspect a propeller on an E-2C Hawkeye on the flight deck of the aircraft carrier USS Theodore Roosevelt (CVN 71) in the Pacific Ocean on Jan. 5, 2021. (MC2 Zachary Wheeler/Navy)