"We need our own long-range air defense system, and today we are taking the first step toward this goal. We started developing an indigenous system, which will be called the Siper. Its first tests are planned to be held by the end of 2021," Erdogan said at a presentation of new domestic defense technologies in Ankara.
READ MORE: 'Turkey's Decision on S-400 Purchase Final, Irreversible' — Former Envoy to US
In April, Russian state arms exporter Rosoboronexport's director general said that Russia had started manufacturing S-400 systems for Turkey.
In mid-April, US Assistant Secretary of State for European and Eurasian Affairs Wess Mitchell said Ankara's purchase of the S-400 air defense missile systems from Russia could negatively affect the delivery of fifth-generation F-35 fighter jets to Turkey.