The US Undersecretary of Defence for Acquisition and Sustainment Ellen Lord stated that the Pentagon wants to keep its fifth generation F-35 jets away from the Russian S-400 systems, fearing the latter might learn to detect the stealth jet. She added that it was the primary reason for denying Turkey the delivery of the jets over the purchase of the Russian air defence systems.
"We do not want to have the F-35 in close proximity to the S-400 over a period of time because of the ability to understand the profile of the F-35 on that particular piece of equipment", Ellen Lord said.
Lord also expressed regret at Turkey's decision to continue preparations for the delivery of the Russian S-400s, including training sessions for the country’s military to operate the Russian equipment.
"The United States was disappointed to learn that Turkey sent personnel to Russia for training on the S-400 system. As we have very clearly communicated at all levels, Turkey will not receive the F-35 if Turkey takes delivery of the S-400 system", she said.
The defence undersecretary further stated that Washington had been forced to initiate the suspension of Turkey’s participation in the F-35 acquisition programme due to Ankara’s actions. She also said the Pentagon would be looking for a replacement for the Turkish factories that produce around 400 unique parts for the F-35s, and aims to find one by 2020.
Reuters reported earlier, citing a purported letter by Acting Defence Secretary Patrick Shanahan to his Turkish counterpart that the US has suspended F-35 training programmes for Turkish pilots, which continued despite the conflict between Washington and Ankara. The US has pressured Turkey into abandoning the purchase of the Russian S-400 systems, threatening to halt F-35 deliveries, to impose economic sanctions, and even exclusion from NATO.
Despite these threats, Ankara has repeatedly reaffirmed its decision to obtain the Russian air defences citing the need to secure its airspace. Turkish President Recep Tayyip Erdogan has on several occasions suggested establishing a working group with the US to iron out their differences over the F-35 and S-400s to make sure the two can operate together. The US so far has ignored the offer, but US President Donald Trump reportedly liked the suggestion in one of his telephone conversations with Erdogan.