Russian S-400 hardware deployment to Turkey continues for fourt day

Delivery of S-400 defense missile system continued on Monday, as eighth Russian plane carrying equipment of the system landed at an airbase on the outskirts of Ankara, Turkey's Defense Ministry said on Monday.
"Delivery of parts of the S-400 Long Range Air and Missile Defense Systems is continuing. In this context, the eighth plane landed at Murted Airbase," the ministry said in a Twitter post.
Later, the ministry also announced the arrival of the ninth plane.
The deployment had started on Friday.
Following protracted efforts to purchase an air defense system from the U.S. with no success, Ankara signed a contract in 2017 to purchase the Russian S-400s.
U.S. officials urged Turkey to buy U.S. Patriot missiles, arguing the Russian system would be incompatible with NATO systems and expose the F-35s to possible Russian subterfuge.
Turkey, however, emphasized the S-400 would not be integrated into NATO systems and would not pose a threat to the alliance.
Turkey has urged formation of a commission to clarify any technical issues, but the U.S. has failed to respond to the proposal.
The U.S. has threatened sanctions over the purchase, with Turkey responding that any sanctions would be met in kind.