"We are certainly aware of their announcement that they plan to install a system in Syria, and obviously we will carefully tack military developments and installations in Syria, particularly as they affect the coalition operations," Cook stated in a briefing.
At the same time, the United States hopes to continue to maintain deconfliction in Syria with Russia through the existing Memorandum of Understanding, Peter Cook added.
"So far we have been able to deconflict operations over Syria through the Memorandum of Understanding in the midst of our disagreements with Russia that has successfully been able to avoid misunderstanding and miscalculation, and we certainly would expect that we continue to avoid any misunderstanding or miscalculation," Cook stated.
Cook added that the United States continues to do everything it can to ensure the safety of its coalition’s aircraft.
"We will continue to do so. And those air cruise as well, I should point out, have right to self-defense," Cook added.
On October 3, State Department deputy spokesperson John Kirby announced in a press release that the United States is cutting off participation in bilateral channels with Russia on sustaining a ceasefire agreement in Syria.
The United States and Russia signed the bilateral MOU in October 2015 to ensure flight safety during combat missions over Syria.
The US-led coalition of more than 60 nations has been carrying out airstrikes against the Islamic State in Syria since September 2014, but without the permission of the legitimate government of Syrian President Bashar Assad or the UN Security Council.