The U.S. Department of State cleared a possible $3.5 billion sale of Patriot air defense systems to Turkey, the Defense Security Cooperation Agency said in a release.

“The State Department has made a determination approving a possible Foreign Military Sale to Turkey of eighty (80) Patriot MIM-104E Guidance Enhanced Missiles (GEM-T) missiles, sixty (60) PAC-3 Missile Segment Enhancement (MSE) missiles and related equipment for an estimated cost of $3.5 billion,” the Tuesday, December 19 release said.

Turkey has also requested the possible sale of four AN/MPQ-65 Radar Sets, four Engagement Control Stations, 10 Antenna Mast Groups (AMGs), 20 M903 Launching Stations, and five Electrical Power Plant (EPP) III. Included in the request are related communications and test equipment, support programs and other training and services, DSCA said.

The total estimated program cost is $3.5 billion.

“This proposed sale will contribute to the foreign policy and national security of the United States by improving the security of a key NATO Ally on the front lines of the fight against terrorism,” the release said.

“Turkey will use Patriot to improve its missile defense capability, defend its territorial integrity, and deter regional threats. The proposed sale will increase the defensive capabilities of the Turkey military to guard against hostile aggression and shield NATO Allies who might train and operate within Turkey’s borders.”

Turkey’s air defense capability gap

DSCA said the sale would “enhance Turkey’s interoperability with the United States and NATO.” Turkey’s purchase of Russian S-400 air defense system has been a point of contention between the two NATO allies, especially as Turkey has previously demanded that any Patriot purchase include transfer of technology.

In 2009, the State Department approved a possible $7.8 billion Patriot sale to Turkey.

It was not clear whether the new approval included technology transfer.

Previously U.S. lawmakers indicated the Trump administration could block the transfer of F-35 stealth jets to Turkey if Ankara acquired the S-400 from Russia. Congress will need to approve the Patriot sale.

Concerns have been raised by Turkey’s NATO allies about data security with the S-400 system, particularly around the F-35. Turkey’s Undersecretariat for Defence Industries (SSM) wants to connect the F-35 systems with the Turkish Air Force information network, HvBS. If the S-400 is also connected to the HvBS, there is a risk that data collected by the advanced Joint Strike Fighter’s sensors may end up being transmitted to Russia.

In April, Ismail Demir, Turkish Defence Industries undersecretary said that Russia had agreed to bring forward to July 2019 the delivery to Turkey of the S-400, but a source told Tass at the time that “the delivery of the two-battalion regiment of S-400 systems to Turkey will be carried out in October 2019.”

In November 2017, Turkish Defense Minister Nurettin Canikli said Turkey had agreed with Eurosam, the European manufacturer of air defense systems, to develop its own missile system. Canikli signed a letter of intent with the defense ministers of France and Italy that month, paving the way for Turkey’s purchase of Eurosam SAMP-T launcher systems and Aster 30 surface-to-air missiles.

This February, Turkey conducted a successful test flight of its HISAR-A short-range, low-altitude air defense missile system.

The HISAR missile family is intended to target aircraft, helicopters, cruise missiles and unmanned aerial vehicles. Turkish manufacturer Rocketsan developed the missile system, while Aselsan developed radar, control systems and vehicles to carry, control and launch the missiles.

HISAR-A has a range of 15km with a maximum altitude of 5,000m, while the HISAR-O has a range of 25km and a maximum altitude of 15,000m. The missiles feature dual-pulse solid rocket motor, midcourse inertial navigation and data link, and terminal guidance using an imaging infrared seeker.

In 2013, after foreign manufacturers proved unable or unwilling to share technology with Turkey, Ankara agreed a $3.4 billion deal with a Chinese state manufacturer – China Precision Machinery Import-Export Corporation – to develop Turkey’s first long-range air and missile defense system. Turkey cited reasons such as favorable technology transfer, a lower price, and earlier delivery.

The sale was dropped in November 2015 after pressure from NATO.

Despite neighboring conflict zones in the Middle East, Turkey doesn’t have a sophisticated long-range air defense system. Over the past five years, NATO deployed up to six Patriot missile defense batteries to protect Turkey’s southern border against missiles fired from Syria.