We want to keep our journalism open and accessible and be able to keep providing you with news and analysis from the frontlines of Israel, the Middle East and the Jewish World. In a letter to leading appropriators, House members called for fresh language last week restricting U.S. funding to support the jets if Turkey buys the S-400.
That would not only guarantee Ankara's planned purchase of 100 F-35s valued at around $100 million each, but also ensure the continued supply of more than 800 components that Turkish firms manufacture for the F-35 as part of a nine-nation consortium.
Roger Wicker shares Shanahan's optimism, telling Wolters that the Turkish insistence on buying the S-400 - which would put North Atlantic Treaty Organisation aircraft operating in Turkey at risk - "is not what one would expect from an ally and it calls into question a lot of things that we've assumed from our long-term ally". Turkish officials say they expect to install Russia's S-400 missile defense system in July - five months before their two F-35s at Luke Air Force Base are scheduled to arrive.
"The United States has been clear that Turkey's acquisition of the S-400 is unacceptable", said acting Pentagon spokesman Charles Summers Jr.
While US lawmakers have threatened in the past to block the delivery of the fighter jets to Turkey, the decision this week was the first concrete move from the Pentagon to do so. Sources familiar with the F-35's intricate worldwide production process and the USA thinking on the issue last week said Turkey's role can be replaced.
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"I concur with this committee's belief that the S-400 and the F-35 are not compatible, and if Turkey proceeds down a path to procure and operate the S-400, they should not get the F-35", Wolters said, adding that the Russian system "speaks a different language than NATO English".
The S-400 Triumf is the most advanced long-range air defense missile system that went into service in Russian Federation in 2007.
Last week Shanahan told Congress he wants Turkey to remain in the F-35 program. It includes 80 Patriot MIM-104E Guidance Enhance Missiles, 60 PAC-3 ballistic missile defense variants, and support equipment for a total estimated cost of $3.5 billion.
"I am very confident in the Patriot proposal that we've delivered to Turkey, its availability, it's pricing, and very importantly, the industrial participation that comes along with the Patriot system". And CNBC reported in September that Russian Federation had begun constructing a site for its air defense system.
"Although they've said, even Erdogan has said, that the S-400 is a done deal, I don't personally think it's a done deal yet", he said. The aircraft is made by Lockheed Martin Corp. "The decision-making calculus in Turkey has narrowed considerably and they may not be fully aware of the consequences".