ANKARA (Reuters) - President Tayyip Erdogan said on Tuesday that an F-35 fighter jet project would collapse if Turkey did not participate, and that it would be an injustice to exclude Ankara over its plan to buy the Russian S-400 air defense system.

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Turkey’s announcement has strained its ties with Washington, which has said it would compromise the security of Lockheed Martin F-35 jets and warned of potential U.S. sanctions.

Like other NATO allies of Washington, Turkey is both a prospective buyer and a partner in production of the F-35, which has been beset by cost overruns and delays, and entered service in the United States in 2015.

Ankara has proposed a working group with the United States to assess the impact of the S-400s, but says it has not received a response from U.S. officials.

Speaking at a defense industry fair, Erdogan said those trying to exclude Turkey from the F-35 project had not thought the process through, and were ignoring its interests.

“We were surely not going to remain silent against our right to self-defense being disregarded and attempts to hit us where it hurts,” Erdogan said. “This is the kind of process that is behind the S-400 agreement we reached with Russia.”

“Nowadays, we are being subject to a similar injustice - or rather an imposition - on the F-35s ... Let me be frank: An F-35 project from which Turkey is excluded is bound to collapse completely,” Erdogan said, adding that Turkey was also rapidly working to develop its own air defense systems.

Erdogan’s comments, his strongest challenge yet to warnings that Turkey could be removed from the F-35 project, came a day after he discussed the purchase of the S-400s and the working group proposal by phone with U.S. President Donald Trump.

U.S. sources have dismissed Turkey’s arguments that it would be impractical to exclude it from F-35 production, and said the trillion-dollar program can proceed without Turkish components.

The broadcaster NTV reported that Turkish presidential spokesman Ibrahim Kalin had also discussed the S-400 system and the F-35 program with U.S. National Security Adviser John Bolton, as well as a date for Trump to visit Turkey.

Turkey said two weeks ago it expected Trump to use a waiver to protect it against penalties over its purchase of the S-400s, after U.S. Secretary of State Mike Pompeo said Ankara could face retribution for the deal under the U.S. Countering America’s Adversaries Through Sanctions Act (CATSAA).