Pro-Iranian militias fired several shells at a US base in eastern Syria's Al-Omar oil field, causing damage but no casualties, the Syrian Observatory for Human Rights said. In retaliation, "heavy artillery has been fired by the (US-led) international coalition" on the town of Al-Mayadeen, controlled by Iranian militias, the Observatory said. Syrian state news agency SANA meanwhile said that "missiles" had been fired towards the US base at Al-Omar, without citing who was responsible. bek/dwo/lg