Turkish President Recep Tayyip Erdoğan said on Wednesday that a U.S. refusal to hand over F-35 stealth fighter jets that Turkey had purchased would mean violating the terms of a contract and amount to theft, the Hürriyet newspaper reported.

The Pentagon last month set July 31 as deadline to eject Turkey from the programme to build and operate the F-35s, if it goes ahead with plans to acquire Russian-made S-400 surface-to-air missile systems. There is also bipartisan support in U.S. Congress to halt the delivery of F-35 jets to Turkey and impose further sanctions.

“If you are looking for a customer, if you have one, and if this customer had made its payments with no delay, how can you refuse to hand over the customer their goods? This means theft,” Hürriyet quoted Erdoğan said during a press conference on his return to Turkey from an official visit to China.

The president said Turkey had so far paid $1.4 billion for the F-35s and had sent its pilots for training in the United States. “They delivered four of them, left the others. We made a contract for purchasing 116 F-35s,” Erdoğan said.

Erdoğan said Turkey had sought to buy U.S.-made Patriot batteries and had resorted to purchase S-400 missile systems from Russia as its offer was declined.

Before a meeting with Erdoğan on Saturday on the sidelines of G-20 summit in Osaka, U.S. President Donald Trump said Turkey had been treated unfairly for buying S-400 missile systems as the former U.S. administration declined to sell Turkey Patriot systems. Following the meeting, Erdoğan said Trump’s words had proven that Turkey would not face sanctions over S-400s.

“The expressions Mr. Trump used for my colleagues during the meeting that day, his attitude to them, is highly appreciated. I told him that I liked his such behaviour,” Erdoğan said.

“They're so easy to deal with. Look at them. Central casting. There's no Hollywood set where you could produce people that look like them,” Trump said on Saturday to compliment the Turkish delegation.