Wess Mitchell, Assistant Secretary of State, issued the warning on Wednesday to the House Foreign Affairs Committee while speaking on behalf of the Bureau of European and Eurasian Affairs.
He said: “Ankara should be mindful of the risks in making strategic concessions to Moscow in order to achieve its tactical objectives in Syria.
“Ankara claims to have agreed to purchase the Russian S-400 missile system, which could potentially lead to sanctions under section 231 of CAATSA and adversely impact Turkey’s participation in the F-35 program.”
The US official cited Turkey’s fluctuating Middle East geopolitical loyalties as a reason for his warning, and accused Turkey of focussing on its own political agenda in the Afrin District against the Kurdish-led Democratic Union Party in Syria (PYD).
He said: “Turkey lately has increased its engagement with Russia and Iran.
“The ease with which Turkey brokered arrangements with the Russian military to facilitate the launch of its Operation Olive Branch in Afrin District – arrangements to which America was not privy – is gravely concerning.”
The top diplomat also encouraged Turkey to remain united with the US in their fight against ISIS.
Mr Mitchell said: “It is in the American national interest to see Turkey remain strategically and politically aligned with the West.”
He noted remaining an ally with Turkey was essential in ensuring “a Syria that is unified and stable emerges from the conflict”.
The official also stressed a united front was key to prevent “Iran, that aids and abets Hezbollah and that seeks the destruction of the state of Israel, from extending its malign influence in the region”.
The US wants Turkey to avoid self-interested, isolationist policies, and remain “a long-term factor in thwarting expansion by Russia and Iran, as outlined in the National Security and National Defence Strategies”.
This comes as the American official accused Russia and the Syrian regime of attempting to disrupt peace talks at the UN in Geneva, by supporting peace negotiations in Astana.
He said: “Moscow’s support for the Syrian regime is intolerable for America and all civilised nations.”
Relations between the US and Turkey have become increasingly tense in recent days, as Turkey rejected appeals from the US to release a detained American pastor, who is accused of aiding terrorist groups.
Mr Trump tweeted is support defence of the pastor, saying: “Pastor Andrew Brunson, a fine gentleman and Christian leader in the United States, is on trial and being persecuted in Turkey for no reason.
“They call him a spy, but I am more a spy than he is.
“Hopefully he will be allowed to come home to his beautiful family where he belongs!”