"We finished this business. For us, taking a step back here is out of the question," Recep Tayyip Erdogan told a private broadcaster about the purchase.

He said Russia will deliver the missiles in July. He added Turkey is also not closed to offers from the U.S. on purchasing the Patriot air defense systems.

U.S. officials suggested Turkey should buy U.S. Patriot missiles rather than the Russian system, arguing the S-400 is incompatible with NATO systems.

But Turkish officials countered that Ankara would not go back on its agreement with Russia, even if it were to also buy Patriots, and also complained that up to now its allies have been unwilling to sell it missile defense.

Patriot missiles are used for defense purposes to shoot down incoming missiles and attack planes. On the economy, Erdogan said despite rising challenges in global economy, Turkey has the capacity to show "positive growth rates" beginning in the second quarter.

Reporter’s code: 50101