"Several external actors have contributed to the militarization process that transformed the [Syrian] unrest into a brutal civil war," the report said.
According to the document, foreign players were engaged in the situation since the very beginning of the uprising and provided different sides in the conflict with financial and military assistance "giving the warring parties, though unequally, the required capabilities to escalate or at least maintain their engagement."
The study also said the participation of foreign military in the Syrian conflict had resulted in a rise of extremism and terrorism in the country and "benefited the extremist groups, such as ISIS [ISIL] and Jabhat Al-Nusra."
Syria's anti-government uprising in the wake of the 2011 Arab Spring has evolved into a civil war that has claimed the lives of some 200,000 people, according to UN estimates. Currently, a number of extremist groups, including ISIL, are fighting against the Syrian army.
In August, 2011 the Human Rights Council established the Independent International Commission of Inquiry on the Syrian Arab Republic to investigate all alleged violations of international human rights law in the country.
The current report by the UN commission is based on 3,556 interviews with eyewitnesses of the Syrian conflict, taken from September, 2011.
