A US-led airstrike on the ISIS terrorist groups embattled enclave in eastern Syria has killed at least six civilians, including four children, a monitor said on Saturday. The Friday strike on the Euphrates Valley village of Baghouz killed 10 ISIS fighters as well as the six civilians, the Syrian Observatory for Human Rights said. Baghouz is part of an enclave of less than 15 square kilometers that is all that is left of ISIS territory in Syria following a grueling Kurdish-led offensive launched with coalition support last May. The Britain-based Observatory said the coalition had stepped up its airstrikes against ISIS since the militants killed 19 people, four of them Americans, in a suicide bombing on a restaurant in the flashpoint northern town of Manbij on Wednesday. "The strikes are continuing, and have intensified since the Manbij attack," AFP quoted Observatory chief Rami Abdel Rahman as saying. The US losses were the biggest since Washington deployed troops in Syria in 2014 in support of the Kurdish-led Syrian Democratic Forces. Previously it had reported just two combat losses in separate incidents. The Manbij bombing rekindled controversy triggered by President Donald Trump last month with his surprise announcement of a full withdrawal from Syria. The US president justified the order with the assertion that the militants had now been largely defeated" in Syria, a claim that the attack threw into renewed question.