BRUSSELS (AP) — The U.S. envoy to NATO says Turkey will be axed from the advance high-tech F-35 fighter jet program if it goes ahead with plans to buy Russian S-400 air defense missiles.

Speaking Tuesday on the eve of NATO talks in Brussels, U.S. Ambassador Kay Bailey Hutchison said "there will be a disassociation with the F-35" if Turkey buys the Russian system, as President Recep Tayyip Erdogan has vowed to do.

Hutchison says "we cannot have the F-35 in any way affected by, or destabilized by, having this Russian system."

The U.S. and other NATO allies have repeatedly complained about the purchase, saying the S-400 is not compatible with other allied systems and represents a security threat.

But Hutchison says Turkey does not appear ready "to retract on the sale."