Ribal al-Assad, the cousin of the Syrian President and the founder of the Organization for Democracy and Freedom in Syria, also noted that although Washington launched its anti-Daesh campaign long before Moscow sent its military aircraft to the Syrian battlefield, it failed to achieve much.
"The Americans came but did nothing," Spain's daily newspaper ABC quoted Ribal al-Assad as saying. The activist described Russia's military engagement in Syria as important.
Moscow carried out a limited counterterrorism campaign in the war-torn country following an official request from Damascus at the end of 2015. Russian forces were largely withdrawn from Syria in March after key goals of the operation were achieved.
In February, Russia and the United States brokered a nationwide ceasefire that has held despite occasional violations. Both countries are also the key endorsers of the UN-backed Geneva peace process. The second round of indirect talks between the government and the opposition concluded this week, with the next one expected to be held in May.
The activist was also critical of Turkey, a country that has done little to prevent radicals from freely travelling to and from the Syrian battlefield and bought oil from Daesh.
