Russia's Foreign Minister Sergey Lavrov has rejected allegations by US State Department spokesman Mark Toner that the use of Iranian military bases violates UN sanctions on Iran. Toners called Russia's latest move in Syria "unfortunate but not surprising." But he added it won't necessarily prevent the US from cooperating with Russia in the fight against ISIL.

"It is- it does not preclude the fact that we will reach some kind of cooperative arrangement with Russia. We continue to pursue that. You know, we're going to continue to speak to Russia, in working groups, or via working groups I guess, about ways that we can put in place a credible nation wide cease fire, have full access to humanitarian assistance, and then again to get negotiations restarted in Geneva. That continues to be our focus," Mark Toner said.

The Pentagon has confirmed that Russian military personnel notified the US-led coalition before Russian bombers launched its first airstrikes from Iran.

Russia's Foreign Minister Sergei Lavrov and his US counterpart John Kerry discussed the Syria situation over the phone on Tuesday. Russia's military operation against ISIL is gaining support from countries in the region. Iraq has already agreed to open its airspace to Russian jets. Russian media reported that Turkey may soon allow Russia's airforce to launch strikes from the Incirlik air base.