The official account for the International Coalition for Operation Inherent Resolve has confirmed that coalition warplanes struck pro-government forces near al-Tanf area near the Syria-Iraq border "posing a threat to US partner forces".
First reports about the possible airstrike appeared today at 16:19 CET on the twitter account of the Media Office for the Revolutionary Forces in Syria, claiming that coalition aircraft targeted "the forces of al-Assad and Iranian militia near the border crossing with Iraq". This comes amid a new offensive launched by government forces and their allies aiming to secure the Iraq-Syria border and the al-Tanf crossing more specifically. The Syrian army would have to capture vast swaths of desert lands from the terror group ISIS aswell as areas under control of coalition supported Maghawir al-Thawra opposition group, as can be seen in the picture below. The approximate location of the airstrike can also be seen.
The rumours quickly spread as al-Jazeeras Syria section twitter account posted a tweet on 16:47 CET saying coalition aircraft targeted pro-government forces and destroyed a tank. At about 18:28 CET, the facebook account of Hammurabi news, a news account affiliated to the coalition trained MaT opposition group and rumoured to be the former spokesperson of the New Syrian Army, published a news report on the alleged strikes seen below. The account claimed that the international coalition targeted elements of the Kata'ib al-Imam Ali group, an Iraqi militia allied to the Syrian government and fighting on its behalf, and syrian government forces near Maqha ash-Shuhaymi area along the N-2 highway connecting Damascus and Baghdad. The government fighters retreated after the strikes were carried out.
As noted earlier, the Iraqi militia Kata'ib al-Imam Ali had been reported to have been struck during the airstrike. The militia group, based in Iraq and the armed wing of the Harakat al-Iraq al-Islamiyah party, is fighting ISIS in Iraq as part of the Popular Mobilization Forces and begun sending fighters to Syria as early as 2015. Pictures posted on social media on the 18th of May confirm the presence of the militia on the front where the strike took place.
On 18:24 CET time, journalist with Buzzfeednews Mike Giglio tweeted that a US official confirmed to him that "the US-led coalition hit Assad regime forces with air strikes in southern Syria today". About two hours later, the official account for the CJTF-OIR confirmed it with the tweets seen below.
The tweets mentioned that despite the coalition firing warning shots, contactingRussia through the deconfliction line and making a show of force with aircrafts the group did not change their path, which led to the airstrikes. An arabic account posted by twitter user @leithfadel, CEO of al-Masdar news, which he received from a military source in Damascus, confirms that the aircrafts fired warning shots, flew on low altitude as a show of force and then struck the convoy. According to the post, the convoy consisted of atleast 5 T-62 tanks, a ZSU-23-4 Shilka anti aircraft vehicle aswell as several trucks and cars and atleast 50 soldiers. The report says two tanks were destroyed, six fighters killed and other three wounded.
According to statements made by an US official towards abcnews, the pro-government troops entered a de-confliction zone and posted a threat to US-allied forces and were thus targeted. The article states that this zone is located around the al-Tanf crossing and had been agreed upon by Russia and the US, however it is unclear when or in what context this zone was agreed upon. The safe zones, agreed upon by Turkey, Iran and Russia during the latest Astana talks on Syria, do not include this area near the Iraqi border.
As has been stated by the officials, these strikes do not present a significant change in policy of the coalition. They were taken as a defense measure to defend the coalition supported groups fighting against ISIS in the area. These strikes are likely not legally conformant. So far, there has been no statements released by the Syrian or Russian governments, so it is unclear what consequences this strike will have. Just like the tomahawk launches ordered by US president Trump in early April 2017, this incident will likely not have a major impact on the situation in Syria. There are however still many questions to be answered, as US-backed rebels present in the area are sooner or later bound to meet with pro-government forces again, as both fight and capture territory from ISIS. It is for now unclear what will happen the next time they get too close to each other again.
UPDATE: This morning, the Russian deputy foreign minister called the strikes "totally unacceptable", saying they "violate Syria's sovereignity and do not help the political process". Senior Russian senator Konstantin Kosachev accused the US of conducting the strike out of anger because the currently ongoing Geneva negotiations are not under their control. The latest rounds of Geneva peace talks on Syria restarted on the 16th of May, but several opposition factions already quit the process.
No further comments were made as to what actions Russia or the Syrian government will take in response to the strike.