Platt then briefly served at the Headquarters Marine Corps in Washington, D.C., before joined U.S. Joint Staff in London, United Kingdom.
While in this capacity, he served briefly as an observer in the Mediterranean during the Suez Crisis in fall 1956.
While in London, Platt was promoted to the rank of colonel on July 1, 1957.

He returned to the United States in summer 1958 and assumed command of Marine Barracks, Washington, D.C., the oldest Post in the Corps.
Platt served in this capacity until June 1960 when he was ordered for instruction to the National War College.
He graduated following June and assumed command of 6th Marine Regiment, 2nd Marine Division at Camp Lejeune, North Carolina on July 10, 1961.
Platt was transferred to the Divisional staff in July 1962 and assumed duty as operations officer under Major General Ormond R. Simpson.
During the Cuban Crisis in October 1962, Platt deployed with part of his division to Guantanamo Bay, Cuba and remained there until December of that year, when crisis faded out.

Platt assumed command of the Basic School at Marine Corps Base Quantico, Virginia, in summer 1963 and was responsible for the training of newly commissioned marine officers.
He remained in this capacity until mid-October 1965, when he received word of his promotion to the rank of brigadier general and deployment to Vietnam.
Platt then briefly served at the Headquarters Marine Corps in Washington, D.C., before joined U.S. Joint Staff in London, United Kingdom. While in this capacity, he served briefly as an observer in the Mediterranean during the Suez Crisis in fall 1956. While in London, Platt was promoted to the rank of colonel on July 1, 1957.
He returned to the United States in summer 1958 and assumed command of Marine Barracks, Washington, D.C., the oldest Post in the Corps. Platt served in this capacity until June 1960 when he was ordered for instruction to the National War College. He graduated following June and assumed command of 6th Marine Regiment, 2nd Marine Division at Camp Lejeune, North Carolina on July 10, 1961. Platt was transferred to the Divisional staff in July 1962 and assumed duty as operations officer under Major General Ormond R. Simpson. During the Cuban Crisis in October 1962, Platt deployed with part of his division to Guantanamo Bay, Cuba and remained there until December of that year, when crisis faded out.
Platt assumed command of the Basic School at Marine Corps Base Quantico, Virginia, in summer 1963 and was responsible for the training of newly commissioned marine officers. He remained in this capacity until mid-October 1965, when he received word of his promotion to the rank of brigadier general and deployment to Vietnam.
Jonas M. Platt