U.S. says offensive in Syria reveals Iran, Russia 'distracted and weakened'

The U.S. national security adviser has said the Syrian opposition's advances in and around Aleppo are linked to a new situation "in which the Syrian government's main backers, Iran, Russia, and Hezbollah, were all distracted and weakened by conflicts and events elsewhere."

The opposition "took a look at three actors who had been pummeling them for years: Iran, Russia, and Hezbollah. They had seen them weaker and more exposed than before, and they tried to take advantage of it," Jake Sullivan told CNN on Sunday.

Noting that he believes the pace of the offensive surprised the Syrian government and other observers in the region, Sullivan said, "But the fact that we have seen activity in Syria coming off of all the other things we have seen in the Middle East and Ukraine and elsewhere, that is something that is the natural result of those adversaries ending up in a weaker strategic position."

About the impact of the recent developments in the Syrian cities of Aleppo and Idlib on the U.S. forces in the region, he expressed his belief that the U.S. forces deployed in Syria to fight the ISIS/Daesh terrorist organization are "not at proximate risk because they are in a different part of the country from where this particular offensive is taking place."

Sullivan, however, added that the U.S. forces are still under a "threat from Iran and Shia-backed militia groups in Iraq."

While acknowledging that the U.S. has labeled HTS a terrorist organization and expressing concerns about "the designs and objectives" of the group, he noted that Washington does not regret the increased pressure on the Assad government.

Referring to the situation as "complicated," Sullivan said Washington is "monitoring closely."

There have been clashes between the Assad regime and the anti-regime armed opposition group Hay'et Tahrir al-Sham (HTS) in Syria's Aleppo and Idlib for about six days.