Russian defense officials say they are getting closer to a deal with the US on air safety in Syria, after aircraft from both countries flew within miles of each other last weekend. The US Pentagon said "progress was made" in the third round of such talks. Russian and US combat aircraft were in visual contact with each other, 10 to 20 miles (15-30km) apart, on Saturday. Russian began air strikes in Syria on 30 September, saying it was targeting Islamic State (IS) militants. But Western countries and Syrian activists say Russian planes have been hitting non-IS targets - a claim Moscow denies. "Positions became closer on key provisions of the future document [on air safety]," the defense ministry said in a statement reported by Russian news agencies. A US official told Reuters news agency that military officials from both sides were finalizing a memorandum of understanding setting out basic air safety procedures over Syrian airspace. In a statement, the Pentagon described talks as "professional and focused narrowly on the implementation of specific safety procedures". Russia said it began its aerial campaign against IS militants and other jihadist groups after a request to help militarily from Syrian President Bashar al-Assad.