- "For Operation Grim Sky, Rainbow Six is deploying Clash and Maverick. Experts in mob behavior and high-precision strikes respectively, they'll also assess the new training facilities at the reworked Hereford Base. Out with the old and in with the new."
— Official Website Description
Operation Grim Sky was the tenth free expansion for Tom Clancy's Rainbow Six Siege. It added two new Operators, one from Delta Force and the other from MPS, that make up Rainbow's Urban Tactical Response Team, codenamed Grim Sky (GSUTR).
It was officially announced on November 19, 2017 and released for Season Pass owners on September 4, 2018, released worldwide on September 11, 2018.