Press TV - A pro-opposition monitoring group says US airstrikes have killed 3,331�civilians in Syria since they began four years ago.

�Among those killed are 826 children and 615 women,� said head of the so-called Syrian Observatory for Human Rights Rami Abdel-Rahman.

The US and its allies have been bombarding what they call Daesh positions inside Syria since September 2014 without any authorization from the Damascus government or a UN mandate. Such air raids began in Iraq in August of the same year.

The aerial assaults, however, have on many occasions resulted in civilian casualties and failed to fulfill their declared aim of countering terrorism.

The Britain-based group�s report comes as Washington claims that its airstrikes killed just 1,061 civilians in both Syria and neighboring Iraq until July 30, 2018.

Rights groups have censured the US and its allies for not pursuing investigations of civilian casualties rigorously enough.

In June, Amnesty International announced that US attacks in Syria's Raqqah last year broke international law by endangering the lives of civilians and may amount to �potential war crimes.�

�The artificially low number of civilian casualties the coalition acknowledges stems in part from poor investigation procedures that fail even to involve on-the-ground research,� it said back then.

US officials dealing with the Syria issue said early this month that "the administration is now resolved to stay in Syria longer than President Donald�Trump previously indicated.�

US marines recently�held eight days of unprecedented�military exercises with militants in southern Syria in what US military spokesman�Colonel Sean Ryan�described the drills as �a show of force�.

The drills were held at the US military outpost in Tanf, located 24 km to the west from the al-Tanf border crossing between Syria and Iraq in Homs.

The US illegally built the military outpost in early 2016 under the pretext of fighting Daesh terrorists, but it has declared a 55 km-radius �deconfliction zone� off-limits to others, providing a safe haven for at least 50,000 militants and their families in the Rukban camp that lies within it.