Turkey has asked the United States to extend the pricing on Raytheon Co’s Patriot missile defense system proposal, two sources familiar with the discussions told Reuters on Monday, a sign that Ankara is keeping its options open in case its talks with the preferred Chinese supplier fall through.

Turkish Prime Minister Recep Tayyip Erdo─čan last week said Ankara would be open to new offers if its talks about co-producing a long-range air and missile defense system with China Precision Machinery Import and Export Corp (CPMIEC) fail.

Turkey’s decision to choose a $3.4 billion Chinese offer over rival bids from Russian, US and European firms has raised concern among Turkey’s Western allies.