Turkey’s President Recep Tayyip Erdogan said on Sunday the S-400 deal with Russia is a most important deal in Turkey’s modern history, TASS reported. 

"Today, the most important agreement in our modern history is the S-400 deal. Purchasing S-400 systems, Turkey is not getting prepared for a war. These missile defense systems are meant to ensure peace and security in our country. We make other steps to improve our defense capacities," Turkey Haberleri reported quoting Erdogan.

The Turkish president once again touched upon the issue of supplying the republic with American’s F-35s.

"The S-400 deal is one topic, while F-35 is quite another topic. BY today, we have paid 1.4 billion US dollars for the F-35s. If Turkey is excluded from the F-35 program, the cost of one aircraft may go up by seven to eight mission. It is not an easy decision. [In this case], they will have to pay back the sum we have paid," Erdogan said.

Deliveries of S-400s to Turkey began on July 12.