ANKARA, Turkey — Turkey’s program for the design, development and production of the country’s first indigenous fighter jet gained pace late in April when two local prime contractors joined forces to outline a production scheme for critical parts.

Meanwhile, in a surprise move, a top Russian aerospace concern expressed interest in developing an engine to power the TF-X, the Turkish fighter aircraft in the making.

On April 26, two strategic local contractors of the TF-X program, military electronics specialist Aselsan — Turkey’s largest defense firm — and Turkish Aerospace Industries, signed a memorandum of understanding to share work on the planned aircraft.

Under the memorandum, Aselsan and TAI, both state-controlled companies, will jointly work to develop critical systems for the TF-X, including a national radar, electro-optical systems, mission-control systems and integration of these systems into the future aircraft.

Earlier this year the Turkish government earmarked an initial investment of 4.817 billion liras (U.S. $1.178 billion) on the conceptual design phase of the TF-X program. The investment plan has been taken under a government incentive scheme.

Turkish procurement officials have confirmed Russian interest in a plan for the development of an engine that would power the TF-X. “There is a Russian interest in this regard, but it is too premature to say if the idea would gain further ground,” an official said.

Pakistan cosies up to Russia, but Moscow doesn’t seem to want to take sides Pakistan and Russia have pledged to improve defense ties, but Moscow appears to be trying to balance its South Asia relations rather than abandon its traditional strategic partner India.

A Turkish diplomat said Turkey’s political ties with Russia were “excellent,” adding that the current political ties paved the way for deeper military and procurement cooperation.

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Causing concern in NATO member capitals, the Turkish government announced Dec. 29 that Ankara and Moscow had finalized a contract for the acquisition and deployment of the Russian S-400 long-range air-defense system on Turkish soil.

The contract is worth some $2.5 billion, and Turkish officials say there may be a follow-on order for a new supply of S-400s, or for the more advanced S-500 system.

Viktor Kladov, director of international cooperation and regional policies at Rostec, a Russian defense conglomerate, told press at the Eurasia Airshow in Antalya, Turkey, that his company would prepare a proposal for cooperation with Turkey on aircraft engines. “We could supply an engine,” he said.

Rostec, established in 2007, brings together 700 Russian entities including specialists in military technology, weapons, military equipment and aircraft engineering.

Turkey’s ambitious TF-X program currently awaits a critical presidential endorsement. After formal go-ahead from President Recep Tayyip Erdogan, the program would race ahead, procurement officials say. The TF-X and other major indigenous development programs are Erdogan’s pet projects.

The next critical stage will be a Turkish decision to choose an engine for the TF-X.

Officials familiar with the program say that talks with a number of potential technology suppliers and their local partners have recently matured. They say the idea is to rely on foreign technology in order to build in the longer term an indigenous engine that will power the TF-X.

In October 2016, engine-maker Rolls-Royce offered a joint production partnership to Turkey with a view to powering planned Turkish platforms and potential sales to third parties. The British company’s proposal involved a production unit in Turkey to manufacture engines for the TF-X, as well as for helicopters, tanks and missiles.

Turkey, UK officials meet over status of Turkish jet program This meeting in Ankara comes at a time when Turkish officials are preparing to select an engine for the TF-X.

A year before that, in October 2015, a memorandum of understanding had been signed between Turkey and Rolls-Royce for technological know-how and a production unit. Under the plan, Rolls-Royce will launch an advanced manufacturing and technology center in Turkey ― the company’s eighth such unit worldwide.

Meanwhile, Tusas Engine Industries, a government-controlled engine maker, is currently working to refine a 20-year road map for the design, development and manufacturing of a local aircraft engine, also with the aim of powering the TF-X. TEI is a sister company of TAI, the prime local contractor of the TF-X program.