Israel made a concerted effort to convince the United States to drop Turkey from the F-35 stealth fighter program out of concern for its qualitative military edge in the region, Channel 12 news reported on Wednesday.

Israel’s diplomatic efforts to stop the sale reportedly began when Turkish President Recep Tayyip Erdoğan purchased the advanced Russian S-400 air-defense system. Israel was concerned that Turkey would leak information about the advanced F-35 to neighboring countries.

Washington, too, seemed concerned about Turkey possessing both F-35s and the S-400 system, saying possession of the planes “cannot coexist with a Russian intelligence collection platform that will be used to learn about its advanced capabilities.” The United States dropped Turkey from the program, despite the latter’s order of more than 100 of the advanced aircraft at a price tag of $1.4 billion.

“President Erdoğan was given a very clear choice. Unfortunately, he has clearly made the wrong one,” said Reps. Eliot Engel (D-N.Y.) and Michael McCaul (R-Texas), respectively top Democratic and Republican members of the House Foreign Affairs Committee.

Israel has ordered 50 F-35s from the United States, with 16 delivered thus far, and is one of the few nations allowed to modify the aircraft. Israel’s version, known as the Adir, is the first F-35 in the world to have been used operationally.

Turkey dismissed concerns regarding the Russian system posing a threat to the American planes and urged Washington to reverse its decision.