He served as a junior officer on several smaller craft, including a combat tour during the Russo-Japanese War on the gunboat Banjō.

[1] Suetsugu subsequently served on the Japanese delegation to the Washington Naval Treaty negotiations in 1921, although he was a prominent member of the Fleet Faction.

During his period in staff assignments at the Imperial Japanese Navy General Staff, he worked on revisions to the Japanese battle plans and strategies, especially targeting the United States Navy, and to opposing the efforts of the Treaty Faction, especially after the signing of the London Naval Treaty.

Noted for his extremely anti-leftist politics, Suetsugu immediately ordered the Tokko special police to begin widespread arrests of known left-wing individuals.

On 7 April 1945, he was Killed in Action (KIA) aboard the battleship Yamato while serving as a Staff officer of Second Fleet and was posthumously promoted to Captain.