On 4 April 2017, a chemical attack on Khan Shaykhun with a banned chemical caused around 100 deaths and around 500 injuries. The OPCW found the attack involved "sarin or a sarin-like substance". The United States and others attribute the attack to the Syrian government. The Syrian government claimed the incident was a fabrication and insisted, despite video documentation, that it was "not clear" that an attack had even happened. Russia claimed the incident was caused by Syrian bombs hitting some sort of rebel sarin cache; experts do not consider the Syrian or Russian claims credible, on multiple levels. On 7 April, the United States struck a Syrian airbase in response to the chemical attack.