It is curious when the S-400 air defence system, which Turkey has obtained from Russia and the first part of it, reached Ankara in July 2019, will be operational.

“We plan to put Russian systems into service in April 2020,” Head of Presidency of Defence Industries Prof. Dr. İsmail Demir, said in November 2019.

Speaking to the Reuters news agency, the senior Turkish official said, “The S-400s will be delayed due to the COVID-19 launch in April.” The official said that it may take several months for the Russian system to be activated and some technical problems continue to be overcome.

US and Turkey's relations were strained to the supply of Russian systems. “We continue to emphasize that the operationalization of the S-400 is the subject of CAATSA's ongoing sanction negotiations and remains a major barrier to NATO relations,” the White House said in a statement.