In June of 1916, Stenseth joined the Minnesota National Guard. Despite his age, he was accepted into the United States Air Service in December of 1916. Following flight training, he was assigned to France in October of 1917 and assigned to the 28th Pursuit Squadron in 1918. Flying the SPAD S.XIII, Stenseth became the highest scoring ace in his squadron and was credited with eight victories in the autumn of 1918.

When the war ended, he remained in the army, returning to the United States in 1920. After commanding various pursuit squadrons, he served in the Philippines during the 1930's and was Military Attache to Finland and Latvia in 1940. In 1941, he founded Nellis Air Force Base and served as its commanding officer on two occasions. Following a distinguished career, Stenseth retired from the United States Army Air Force as a Brigadier General in 1947.