In a letter to Secretary of State Mike Pompeo, Democratic Senator Chris Van Hollen and Republican Senator James Lankford seek explanations for reports that Turkey has activated the Russian S-400 anti-aircraft missile system which it tests on US-made aircraft of allied countries.

According to DefenseOne, Greek press reports on Monday claimed that Turkey had activated the Russian S-400 air defence system to track the Hellenic Air Force and the F-16s returning from the multilateral “EUNOMIA” exercise that was completed on the 28th of August.

Also read: Greek F-16s landed in Paphos | VIDEO

The two senators recall that last year Turkish F-16 jets flew over Ankara as part of a test of the S-400 system, while underlining the estimates of US government officials, who said that the Russian system could provide Russia with a back door to spy on NATO allies.

Also read: Impressive footage from the aeronautical exercise “EUNOMIA” VIDEO

“To-date,” the letter states, “the administration has not imposed sanctions on Turkey for its purchase of the S-400 under Section 231 of the Countering America’s Adversaries through Sanctions Act. Reports of this activation make clear that Turkey has no intention of reversing course and divesting of this system. Additionally, the slow pace at which the Department of Defense is moving to remove Turkey from the F-35 supply chain has no doubt emboldened President Erdogan. Turkey’s recent reported activation of the S-400 system to detect the U.S. F-16 underscores our grave concerns about Russia’s ability to access sensitive data.”

The two senators urge Foreign Minister Mike Pompeo to impose sanctions on Turkey, as provided by the relevant legislation and at the same time ask him to inform them by October 14:

• Did Turkey activate the S-400s to detect F-16 fighter jets returning from the “Eunomia” exercise?
• Has Turkey integrated Link 16, NATO’s tactical data link, into the S-400 system? If so, could this integration enable Russia to gather information on NATO allies?”

#Turkey is planning to conduct a comprehensive test of the S-400 missile-defense system it purchased from #Russia next week. pic.twitter.com/8VsAmm8fqo

— Nikhil Choudhary (@NikhilCh_) October 7, 2020

Also read: No F-35s to Turkey | US Senate Resolution

According to DefenseOne and other international media, Turkey has used the anti-aircraft and anti-missile system in the past in a test exercise involving its own F-16 aircraft. On Tuesday, Bloomberg reported that Ankara plans to test the system next week at a location in the Black Sea province of Sinop.

There, the missile system, which has a range of 400 kilometers, could monitor US aircraft, which often cross the Black Sea. Bloomberg claims that Turkey “does not activate the system, but simply controls the equipment as well as the readiness of Turkish personnel,” which is very vague and leaves many possibilities open. “If they activate the S-400s, they are probably using them in some way,” said Thomas Karako, a missile defence expert at the Center for Strategic and International Studies think tank in Washington.

“But use is not the criterion for CAATSA sanctions. “The burden of proof is not to determine the ‘improper’ use – say, towards fellow NATO allies,” Karako said. “The CAATSA language is about taking delivery of weapons from Russia.”

Also read: The United States opposes the acquisition of S-400 by Turkey and warns of the threat of sanctions

The State Department spokesman did not rule out the use of CAATSA

“We continue to object strenuously to the purchase of the S-400 air defence system by Turkey and we are deeply concerned about reports that Turkey is continuing its efforts to operate the S-400,” the foreign ministry spokesman said.

“We continue to stress at the highest levels that the S-400 deal remains a significant obstacle to bilateral relations as well as to NATO, as it poses the risk of possible CAATSA sanctions.” Turkey has issued air warnings for the northern city of Sinop amid reports that the Ankara army intends to test the Russian S-400 air defence system within the next two weeks.

Also read: US senator proposes to buy S-400 from Turkey | Russia’s reaction

“Launches will take place” up to 200,000 feet between October 13-16 near the Black Sea coastal town of Sinop, a “warning” issued by the Turkish government stated. Another notice states civil aviation routes to the area that would be closed during the exercise. Unmanned aerial vehicles are also scheduled to fly in the area.

Footage shows military equipment, purportedly S-400 air defense batteries, on the move in Turkey. On Friday, @TurkishMinuteTM published an exclusive piece about the tests to take place 5-16 Oct, citing official correspondence. pic.twitter.com/0T25BZhWMF — Turkish Minute (@TurkishMinuteTM) October 6, 2020

In the Russian Armed Forces, the S-400 is the successor to the S-300 PMU-2. It has an increased ability to detect stealth technology aircraft. It can engage 36 targets at the same time and has very high precision and long-range missiles. The S-400 is considered one of the best SAM (Surface to Air Missiles) systems in service today, and its successor, the S-500, is already being developed.

With information from: CNA / DefenseOne / Reuters / Al-monitor