Turkish President Recep Tayyip Erdogan says Turkey will not go back on its agreement with Russia and may subsequently look into buying S-500 the next generation system.

In a televised interview, he said Turkey concluded the S-400 issue, signed a deal with the Russians, and will start co-production.

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