ALEPPO: The White House says it is “confident” Bashar al-Assad’s government was behind an apparent chemical attack that killed at least 58 people in north-west Syria. The Syrian Observatory for Human Rights reported that strikes on Khan Sheikhoun by Syrian government or Russian jets had caused many people to choke. Later, aircraft fired rockets at local clinics treating survivors, medics and activists said. Syria’s army denied the government had used any such weapons. In a statement, President Donald Trump condemned what he called “these heinous actions” by the Bashar al-Assad regime. “It is clear that this is how Bashar al-Assad operates,” the US Secretary of State Rex Tillerson said, “with brutal, unabashed barbarism.” The United Kingdom, United Nations and France, among others, also condemned the incident, which would, if confirmed, be one of the deadliest chemical attacks in Syria’s civil war. Pro-government journalists later cited military sources as saying there had been an explosion at an al-Qaeda chemical weapons factory in Khan Sheikhoun that was caused either by an air strike or an accident. The defence ministry of Russia, President Assad’s ally, insisted it had not carried out any air strikes in the vicinity.