At least 15 civilians have been killed in northeastern Syria in airstrikes carried out by the so - called US - led coalition purportedly hitting Daesh positions in the Arab country, a monitoring group says. The so-called Syrian Observatory for Human Rights said that 20 more people also sustained injuries in the Tuesday US-led attacks on the town of al-Shadadi in Hasakah province. The UK-based monitoring group added that the overall death toll was likely to rise. Since September 2014, the US along with some of its allies has been conducting air raids against what are said to be the Daesh Takfiri terrorists inside Syria without any authorization from Damascus or a UN mandate. The air assaults in Syria are an extension of the US-led aerial campaign against purported Daesh positions in Iraq, which started in August 2014. The US-led strikes have killed scores of civilians in Syria ever since. Syria has been gripped by foreign-backed militancy since March 2011. According to a new report by the Syrian Center for Policy Research, the conflict has claimed the lives of over 470,000 people, injured 1.9 million others, and displaced nearly half of the country’s pre-war population of about 23 million within or beyond its borders.