Russia's state arms exporter, Rosoboronexport, says it will begin delivering its advanced S-400 antiaircraft missile systems to Turkey in 2019.
Rosoboronexport also said on August 21 that it would stop conducting its sales to foreign customers in U.S. dollars, allowing purchases in local currencies.
The announcement comes as Turkey faces a crisis over its weakening lira currency amid worsening relations with the United States.
President Recep Tayyip Erdogan said on August 20 that Turkey's currency crisis is the result of an "attack" on his country's economy.
Washington has voiced concern over NATO-member Turkey's purchase of Russian-made S-400 missiles, arguing that its deployment could risk the security of several U.S.-made weapons that Ankara uses -- including the F-35 warplane.
The United States has also imposed sanctions against Turkey over the continued detention in the country of an American pastor.
Washington has also increased tariffs on Turkey.
Erdogan said the aim of those he blamed for Turkey's currency crisis was to bring "Turkey and its people to their knees."
But he said Turkey had the power and ability to overcome the crisis.
U.S. President Donald Trump last week signed a defense spending bill that includes delaying the delivery of F-35 fighter jets pending a Pentagon report.
U.S. lawmakers have been working to block the delivery in response to the American pastor's arrest and Turkey's pledge to buy Russian S-400 missile systems.