On 4 April, Syrian President Bashar al-Assad's regime apparently targeted the town of Khan Sheikhoun, in Idlib province, with chemical weapons (CW) – the nerve agent sarin, to be precise. US President Donald Trump's initial reaction was muted almost to the point of acquiescence, White House Press Secretary Sean Spicer having described the Assad regime as a 'political reality that we have to accept' a few days before the CW attack. US Ambassador to the UN Nikki Haley's strong statement of condemnation at the UN Security Council, however, hinted at a shift in attitude and a forceful unilateral US response. Within 63 hours, Trump had completely changed his mind, ordering the launch on 6 April of 59 Tomahawk land-attack cruise missiles (TLAMs) from two US destroyers deployed in the Mediterranean Sea on Shayrat Air Base, the airfield in Homs from which the regime planes that delivered the CW strikes had taken off. His daughter Ivanka's distress over the CW attacks reportedly influenced Trump's decision.
The Trump administration is at least tentatively casting this response as a stand-alone deterrent to further regime use of high-end CW, and is not planning to follow it up with additional major military action that might cleave towards regime change, leaving US Syria policy substantially intact for the moment. While the TLAM strikes may therefore lower the threshold of further US military action against the regime, serve as a demonstration of US resolve to China and North Korea, and constitute a politically useful signal that Trump is not beholden to Russia, they are not likely to advance peace in Syria. Less than two days after the strikes, Syrian planes were again in the air and pummelling Khan Sheikhoun.