Direct proof of use
Tomahawk use in the 2011 Syrian Civil War is directly documented in the U.S. strike on Shayrat Airfield on April 6-7, 2017. The Pentagon said U.S. forces launched 59 Tomahawk Land Attack Missiles from the destroyers USS Porter and USS Ross in the Eastern Mediterranean Sea, targeting aircraft, hardened aircraft shelters, petroleum and logistics storage, ammunition bunkers, air-defense systems, and radars at the Syrian air base in Homs governorate.
A second documented episode came during the U.S., UK, and French strike operation on April 13-14, 2018. In the Pentagon's post-strike briefing, Joint Staff Director Lt. Gen. Kenneth F. McKenzie Jr. said the Barzah Research and Development Center was struck with 57 Tomahawk land-attack cruise missiles and 19 JASSMs, while the Him Shinshar chemical-weapons storage facility west of Homs was struck with a mix that included nine U.S. TLAMs. He also identified the U.S. launch platforms: USS Monterey fired 30 Tomahawks from the Red Sea, USS Laboon fired seven from the Red Sea, USS Higgins fired 23 from the North Arabian Gulf, and USS John Warner fired six from the Eastern Mediterranean.
Sources: Pentagon Shayrat Strike Statement, CENTCOM Shayrat Strike Story, DoD Syria Strike Briefing
Timeline
The first Tomahawk episode followed the April 4, 2017 chemical attack in Khan Sheikhoun. The Pentagon statement placed the U.S. strike at about 8:40 p.m. EDT on April 6, which was 4:40 a.m. on April 7 in Syria, and said Shayrat Airfield was targeted because U.S. intelligence assessed that aircraft from the base conducted the chemical attack.
The second episode followed the April 7, 2018 Douma attack allegation and was conducted during the night of April 13-14, 2018. U.S. officials described a 105-weapon coalition package against three Syrian government chemical-weapons-related targets: Barzah near Damascus and two Him Shinshar sites west of Homs. Tomahawks formed the largest U.S. naval component of that strike package.
Sources: Pentagon Shayrat Strike Statement, DoD Syria Strike Briefing, Pentagon Syria Strikes Story
Operational role
In this conflict, Tomahawk appears as a U.S. naval long-range precision-strike weapon rather than a system transferred to Syrian battlefield parties. The documented users were U.S. Navy surface ships and a U.S. Navy submarine operating outside Syrian territory, and the documented targets were Syrian government airfield and chemical-weapons-related facilities.
The 2017 strike was a single-country U.S. operation against Shayrat Airfield. The 2018 use was part of a coordinated U.S., UK, and French package in which Tomahawks were combined with U.S. JASSMs, British Storm Shadows, French SCALP missiles, and French naval cruise missiles. Public official sourcing supports the launch platforms, missile counts, broad target sets, and stated U.S. rationale; it does not show Tomahawk possession or use by Syrian government, opposition, Islamic State, or SDF-aligned forces.
Sources: Pentagon Shayrat Strike Statement, DoD Syria Strike Briefing, Pentagon Syria Strikes Story