"We are committed to a political process that is with and by the Syrian people. The Syrian people get to decide who will lead them and what kind of a government they will have. We are not committed to any kind of regime change. We are committed to a change in the behavior of that regime."

The US military presence in Syria does not pursue its break-up, Jeffrey said.

"The United States has supported the territorial integrity of Syria at every point in this conflict and before, and we will continue to do so. The presence of American forces carrying out anti-terrorist operations does not indicate any desire to break apart a country," he said.

Commenting on Russian delivery of S-300 defense system to Syria, Jeffrey said Washington believes that the deliveries of Russian S-300 air defense systems to Syria raise the possibility of the repetition of the mistake that triggered the crash of a Russian Il-20 plane near Syria.

"Now, concerning the S-300: as we have said before, we see this as a dangerous escalation. And we think that it’s a tragedy that — one tragedy, which was the loss of a Russian aircraft and I believe 15 lives, due to mistaken military action on the part of the Syrian military — it leads to giving the Syrian military a greater capability to make mistakes like this in future. So therefore we would urge the Russians to be very careful with this," Jeffrey said.

The Il-20 was downed near Syria on September 17 by a missile launched by Syria's S-200 air defense system. The Russian Defense Ministry put the blame for the crash on the Israeli Air Force that was carrying out airstrikes in the Syrian province of Latakia at the time of the incident, arguing that the Israeli jets used the Il-20 as a shield against the Syrian air defense systems and that Israel notified Russia of its operation only a minute before the attack.

Jeffrey was asked in an interview with RIA Novosti and Kommersant whether Syria would be on the agenda of the possible meeting between Putin and Trump at the G20 summit in Argentina on November 30-December 1.

"Well first of all there is no official confirmation that the meeting will happen. Were a meeting to happen, if you look at the experience of past meetings between President Trump and President Putin, Syria plays a very, very important role," Jeffrey said.

The diplomat stressed that Syria was "very much on the mind" of Trump, adding that the US president focused a great deal of attention to the matter when speaking at the United Nations in New York.

"Those were his words — to de-escalate the conflict and revitalize the political process. That is his policy. He will talk about that at length with anyone willing to talk with him. So we’ll have to see if there is a meeting," Jeffrey noted.

Kremlin aide Yury Ushakov said on Monday that the date for Putin-Trump talks in Argentina was being negotiated.

Reporter’s code: 50101