by water impulse (horizontally via the torpedo tube), a solid-fuel booster is ignited to propel the missile and guide it out of the water. After achieving flight, the missile's wings are unfolded for lift, the airscoop is exposed and the turbofan engine is employed for cruise flight. Over water, the Tomahawk uses inertial guidance or GPS to follow a preset course; once over land, the missile's guidance system is aided by terrain contour matching (TERCOM). Terminal guidance is provided by the Digital Scene Matching Area Correlation (DSMAC) system or GPS, producing a claimed circular error probable of about 10 meters. The Tomahawk Weapon System consists of the missile, Theater Mission Planning Center (TMPC)/Afloat Planning System, and either the Tomahawk Weapon Control System (on surface ships) or Combat Control System (for submarines). Several versions of control systems have been used, including: v2 TWCS – Tomahawk Weapon Control System (1983), also known as "green screens," was based on an old tank computing system. v3 ATWCS – Advanced Tomahawk Weapon Control System (1994), first Commercial Off the Shelf, uses HP-UX. v4 TTWCS – Tactical Tomahawk Weapon Control System, (2003). v5 TTWCS – Next Generation Tactical Tomahawk Weapon Control System. (2006) On August 18, 2019, the United States Navy conducted a test flight of a Tomahawk missile launched from a ground-based version of the Mark 41 Vertical Launch System. It was the United States' first acknowledged launch of a missile that would have violated the 1987 Intermediate-Range Nuclear Forces Treaty, from which the Trump administration withdrew on August 2 after Russia broke it. Munitions The TLAM-D contains 166 sub-munitions in 24 canisters: 22 canisters of seven each, and two canisters of six each to conform to the dimensions of the airframe. The sub-munitions are the same type of Combined Effects Munition bomblet used in large quantities by the U.S. Air Force with the CBU-87 Combined Effects Munition. The sub-munitions canisters are dispensed two at a time, one per side. The missile can perform up to five separate target segments which enables it to attack multiple targets. However, in order to achieve a sufficient density of coverage typically all 24 canisters are dispensed sequentially from back to front. Navigation TERCOM – Terrain Contour Matching. A digital representation of an area of terrain is mapped based on digital terrain elevation data or stereo imagery. This map is then inserted into a TLAM mission which is then