US Vice-President Mike Pence has warned Turkey against buying a Russian S-400 anti-aircraft missile system that Washington sees as a threat to US jets.
He said Turkey “must choose” between remaining a key Nato member or risk the security of that partnership “by making such reckless decisions”.
Turkey responded that the purchase of the advanced system was a done deal.
Ankara has been establishing closer links with Russia after recent souring of its ties with the US and Europe
Turkey has the second-largest army in Nato, a 29-member military alliance set up to defend against what was at the time the Soviet Union.