U.S. Marine Corps M-18 Smoke Grenades are stacked for Final Exercise 3 during Weapons and Tactics Instructor Course (WTI) Course 2-15 near Yuma, Ariz., April 25, 2015. WTI is a seven-week event hosted by Marine Aviation Weapons and Tactics Squadron One (MAWTS-1) cadre. MAWTS-1 provides standardized tactical training and certification of unit instructor qualifications to support Marine aviation Training and Readiness and assists in developing and employing aviation weapons and tactics. (U.S. Marine Corps photo by Lance Cpl. Jodson B. Graves, 2nd MAW Combat Camera/Released)