Turkey aims to make an definitive decision in about six months on whether to co-produce an air and missile defense system with a Chinese firm that is under U.S. sanctions, a senior Turkish defense official said on Thursday.

Turkey’s NATO allies voiced concern when it said in September it had chosen China’s FD-2000 missile defense system over rival offers from Franco/Italian Eurosam SAMP/T and US-listed Raytheon Co. It said China offered the most competitive terms and would allow co-production in Turkey. The deal would mark a breakthrough for China in its bid to become a supplier of advanced weapons. But the Turkish official, Murad Bayar, said it was not a foregone conclusion that Ankara would end up signing the $3.4 billion deal with the China Precision Machinery Import and Export Corp (CPMIEC).

“Our procurement process is such that we begin with the first company with the intention to sign the contract but of course if there are difficulties that are not foreseen … we go down through the rank,” Bayar, Turkey’s Undersecretary for Defense Industries, said at a NATO industry forum. He said typically such contract negotiations would take six to 12 months but that the complexity of the current deal made him hesitant to be any more precise. “The immediate goal for us is in about six months to come to a reasonable level in our contract negotiations (with China) and to understand whether it is possible to implement this program with the first option.”