Turkey has received the first parts of a Russian S-400 missile defence system despite opposition from the US.
The shipment arrived in an airbase in the capital Ankara on Friday, the Turkish defence ministry says.The move will anger the US, which has warned that Turkey cannot have both the S-400 anti-aircraft defence system and US F-35 fighter jets.
Turkey and the US are Nato allies - but Turkey has also been establishing closer links with Russia.
Turkey has signed up to buying 100 US F-35s, and has invested heavily in the F-35 programme.
However, US defence officials have said they do not want the F-35 jets to be near S-400 systems - because they fear Russian technicians will be able to access the F-35's vulnerabilities.
How does the S-400 work?
Long-range surveillance radar tracks objects and relays information to command vehicle, which assesses potential targetsTarget is identified and command vehicle orders missile launch
Launch data are sent to the best placed launch vehicle and it releases surface-to-air missiles
Engagement radar helps guide missiles towards target