In the defense of the Deir Ezzor Airport, the Syrian military has long depended on an army base in Jebel Tharda to repel ISIS advances. That base has been lost this weekend, after a disastrous series of US-led airstrikes killed a large number of Syrian troops defending the base, and ISIS quickly overran what was left.

For over 20 minutes, the coalition warplanes attacked the base. According to the Syrian Observatory for Human Rights, the attack killed at least 83 Syrian troops and wounded 120 others. The US Central Command claimed they thought the base belonged to ISIS.

It does now. With the forces decimated by the US attack, ISIS quickly overran the base. Syrian state media claimed an ongoing effort to recover the site, but it does not appear to have been successful yet, as ISIS managed to shoot down a Syrian warplane, flying out of Deir Ezzor Airport, over Jebel Tharda.

The US continued attacking the Syrian troops until they were warned by Russia that they were attacking the wrong site. The US has since expressed “regret” but also condemned Russia for calling an emergency UN Security Council meeting over the matter, insisting everyone knows the US “would not intentionally strike a known Syrian military unit.”

Protracted anti-Russia speeches by the US Ambassador ended the emergency meeting prematurely, and has led Russian officials to remark that the incident is “suspicious” and reflective of the US refusal to coordinate in the air war against ISIS.

The US and Russia had brokered a ceasefire which went into effect last week, and included the Syrian government, meaning the airstrikes were a major violation of that ceasefire. Though the ceasefire was supposed to, after seven days, give way to a new coordinated US-Russia bombing campaign, it is unclear at this point if Russia has any appetite to attempt this anymore, as US officials continue to complain that they don’t trust Russia to keep up their end of the bargain.