Turkish President Recep Tayyip Erdogan has revealed that Russian S-400 air defence systems may start being delivered to Turkey in the first half of July.

Turkish President Tayyip Erdogan said on 16 June that Ankara would receive the Russian S-400 missile defence system "very soon," Reuters reported Tuesday.

The statement came several days after a brief conversation between Russian President Vladimir Putin and Erdogan in Dushanbe prior to the start of the Conference on Interaction and Confidence-Building Measures in Asia (CICA).

Erdogan has said on multiple occasions that Turkey would not backtrack from its deal with Russia on purchasing the high-tech S-400 missile defence system.

Washington has repeatedly warned that the S-400 is not compatible with NATO military equipment standards, adding that the Russian air defence systems presents a threat to the F-35 fighter jet. Washington has threatened to impose sanctions on Ankara under the Countering America's Adversaries Through Sanctions Act (CAATSA) and take back Ankara's F-35 fighter jets if the Turkish government takes delivery of the Russian missile defence systems.

Ankara has reiterated that the purchase of the S-400 is its affair, while emphasizing that the Russian missile defence network is not connected to the security of the alliance, the US or the F-35 program, and that the decision to acquire the S-400 “does not target a third country”.

In December 2017, Moscow and Ankara signed an agreement for the delivery of the cutting edge S-400 systems. The Turkish decision to purchase the Russian missile defence systems angered the former's closest NATO ally, the United States. Washington has repeatedly relayed its concerns to Turkey that the systems will be incompatible with NATO standards, but Turkey has rebuffed all concerns.