The U.S. Marine Corps version of Lockheed Martin's F-35 Joint Strike Fighter, F-35B test aircraft BF-2 flies with external weapons for the first time over the Atlantic test range at Patuxent River Naval Air Systems Command in Maryland on Feb. 22, 2012. (Reuters File photo)

ANKARA, April 18 (Xinhua) -- Turkey is not just a buyer of U.S. F-35 fighter jets but also a technology partner in the production program, Turkish presidential spokesman Ibrahim Kalin said on Thursday.

"Turkey is, and will continue to be, a partner of F-35 technology. We are not just a client or buyer of F-35s, " Kalin told reporters following a cabinet meeting in the capital Ankara.

Turkey is one of the participants in the U.S. F-35 international program, but its decision to buy the advanced Russian S-400 surface-to-air missile system has strained its relations with the U.S., which threatened to suspend the sale of F-35 jets to Turkey unless it scraps the S-400 deal.

Last week, Turkish President Recep Tayyip Erdogan reiterated that Turkey's procurement of the Russian S-400 air defense systems is a national security deal, criticizing U.S. for halting the F-35 deliveries.