Colonel Pastel was commissioned on 24 May 1996 after graduating from the United States Naval Academy. After attending The Basic School and the Field Artillery Officer Basic Course, he reported to 2d Battalion, 11th Marines in Camp Pendleton, CA. He remained there from 1997 to 2000 and served as a forward observer, guns platoon commander, fire direction officer, and battery executive officer. He also deployed twice with Battalion Landing Team 2/5 as part of the 31st Marine Expeditionary Unit.
In 2000, he reported to The Basic School (TBS) for instructor duty. While at TBS, he served as the head fire support instructor, staff platoon commander, and company executive officer. From 2003-2004 he attended Expeditionary Warfare School.
Next, Colonel Pastel reported to 1st Battalion, 10th Marines in 2004. During this tour he served as the Headquarters Battery Commander, Headquarters Company Commander for Headquarters Battalion, 2nd Marine Division, Battalion Operations Officer, and Battalion Executive Officer. As the Headquarters Company Commander, he deployed to Ramadi, Iraq in support of Operation IRAQI FREEDOM III-2.
From 2007-2008, he attended the Marine Corps Command and Staff College. After finishing school, he reported to Manpower Management Enlisted Assignments (MMEA) and six months later was selected to be the Junior Aide to the 34th Commandant of the Marine Corps. He served as Junior Aide from December 2008 to November 2010. Remaining in the Pentagon, he reported to the J-3, Joint Operations Directorate DDRO, JODCENT and served in various action officer billets until 2013.
In June 2013, Colonel Pastel took command of 1st Battalion, 11th Marines at Camp Pendleton, CA. After changing command in January 2015, he assumed duties as the 11th Marines Executive Officer. In the summer of 2015 he reported to Fort McNair to attend The Eisenhower School, National Defense University. Next he reported to the 5th Marine Expeditionary Brigade in Bahrain to serve as the Current Operations Officer.
In 2017 he was selected to be a Commandant of the Marine Corps Senior Fellow at the Center for a New American Security in Washington, D.C. After completing this fellowship in 2018 he reported to the Deputy Commandant for Information (DC I) to serve as the Director, Plans and Strategy Division. He completed his tour in DC I in June 2020 and subsequently reported to Marine Barracks Washington for his current assignment as the Commanding Officer.