On 10 April, the White House reported that US President Donald Trump cancelled his trip to a meeting of the a Summit of the Americas in Lima, Peru to concentrate on a US response to the Syrian government’s alleged use of a nerve agent, which reportedly killed dozens of civilians in the Damascus suburb of Douma on 7 April. Military options for the US range from an enhanced set of airstrikes similar to those performed last April that targeted the Shayrat airbase, to conducting airstrikes that will actually attempt to undermine the Syrian regime via command and control strikes. According to US media, the first of these options, one that includes cruise missile strikes against an expanded list of targets, such as airports, suspected chemical weapons munitions factories, and air defense batteries, remains the most likely of the pair, as the president wants to demonstrate US resolve without greatly expanding the US presence within the country.
- There is a high probability that US military strikes will commence within the next 48 hours. These are most likely to take the form of cruise missile strikes launched from naval vessels in the Gulf and/or Mediterranean Sea, up to combined airstrikes by strategic bombers and cruise missiles. In the event of partner countries taking part in airstrikes (France, Saudi Arabia and potentially Israel), activity is likely to be staged over a period of some days.
- There will be a slightly increased risk of collateral damage to commercial aircraft on the ground at Syrian airports controlled by the government, including Damascus International Airport.
- All commercial airports in Syria are also used as military bases by the Syrian government, and are at risk of being targeted by the US. However, the accuracy of US cruise missiles or precision bombs minimises the likelihood of collateral damage to persons or property at civilian terminals. Latakia Airport is at a much lower risk of US strikes due to its role as a Russian air base.
- The anticipated use of S-200 missiles by the Syrian Army in response to a US attack increases the risk of unintentional shootdown to any aircraft, including commercial airliners, within its operating range of 300 km. All variants of the S-200 have maximum altitude range surpassing commercial airline cruising altitude. This includes aircraft approaching Beirut’s Rafic Hariri International Airport and, to a lesser extent, Amman’s Queen Alia International Airport, which are both located less than 100 km from the Syrian border.
- The risk in Jordanian airspace is lower due to the deployment of US Patriot missile-defence batteries, and significantly lower in Israeli airspace, due to the country’s extensive missile defence shield. Separately, there is a risk of stray Syrian air-defence missiles falling on neighbouring territory and causing collateral damage and casualties on the ground.