The Syrian military rushed reinforcements to the country's northwest and launched airstrikes on a major city Sunday in an attempt to push back insurgents who seized the country's largest city of Aleppo in a surprise offensive in recent days.

Diminished support for the Syrian government from Iran, Hezbollah and Russia enabled opposition forces to take the initiative and seize new territory.

National Security Adviser Jake Sullivan tells CNN’s Kasie Hunt that as of right now, the rebel offensive in Syria does not put US forces in the region at risk.