Turkey's Defence Minister Fikri Isik answers a question during an interview with Reuters in Ankara, Turkey, August 5, 2016. REUTERS/Tumay Berkin

ANKARA (Reuters) - Turkey’s talks with Russia about the purchase of the S-400 air missile defense system have reached a “final stage”, although this does not mean a deal will be signed immediately, Defense Minister Fikri Isik said on Friday.

Isik also told a news conference that NATO countries have not presented a “financially effective” offer on an alternative defense system. NATO member Turkey in 2015 canceled a $3.4 billion tender for a long-range missile defense system that had been provisionally awarded to China.

Turkey then said it would consider developing a missile system locally, but that stance later shifted.

“It is clear that Turkey needs a missile defense system but NATO member countries have not presented on offer which is financially effective,” Isik told a news conference.

“Work on the S-400 has reached a final point. But the final stage does not mean ‘let’s sign a deal tomorrow morning’”.

He said Turkey would not be able to integrate the S-400 into the NATO system.