Turkey will seek compensation for its removal from a US-led stealth fighter jet programme, Turkish President Recep Tayyip Erdogan said.
Mr Erdogan said he might raise the matter in a meeting with US President Joe Biden on the margins of a Group of 20 meeting next month.
On a flight from Sochi after meeting Russian President Vladimir Putin on Wednesday, he said there would be no “turning back” from a deal with Russia for S-400 advanced missile defence systems two years ago.
That deal led to Nato member Turkey’s removal from the international programme producing F-35 fighter jets. Ankara plans to buy more S-400s.
Mr Erdogan said he hoped to meet Mr Biden at the G20 meeting in Rome to discuss the project, including a $1.4 billion payment Turkey had made before it was removed from the programme.
Another meeting between the Turkish and US leaders could take place on the sidelines of November's Cop26 climate conference in Glasgow, Scotland, Mr Erdogan told private Turkish news channel NTV.
“We made a $1.4bn payment. What will become of that?” he asked. “We did not, and do not, earn this money easily. Either they will give us our planes or they will give us the money.
“The S-400 process continues. There is no turning back.”
The US strongly objects to Nato members using the Russian system, saying it poses a security threat to the F-35s.
Turkey insists the S-400’s parts could be used independently, without being integrated into Nato systems, and therefore pose no risk.
The US also imposed sanctions on Turkey under a 2017 law aimed at opposing Russian influence. It was the first time the law was used to penalise a US ally.
Mr Erdogan’s talks with Mr Putin in the Black Sea resort of Sochi focused deepening defence co-operation between Turkey and Russia, including partnerships for aircraft engines, fighter jets and submarines, he said.
Russia also could be involved in the construction of Turkey’s second and third nuclear power plants, and of a space launch platform, Mr Erdogan said.
He travelled to Sochi to discuss the situation in Syria, where Turkey and Russia back opposing sides in the conflict.
Russia is the main ally of the Syrian government, while Turkey supports groups that have fought to unseat Syrian President Bashar Al Assad.
But Russian and Turkish troops have co-operated in Syria’s north-western Idlib province, the final holdout of rebel forces, and in seeking a political solution for the country's war.
Mr Erdogan said he and Mr Putin agreed to continue to work together towards restoring calm in Idlib.