Turkish President Recep Tayyip Erdogan would take up his country’s ouster from the US-led F-35 stealth fighter jet program in a meeting with President Joe Biden on the sidelines of the COP26 climate summit in Glasgow, the Turkish leader said on Wednesday. 

“Most likely, we will have a meeting in Glasgow instead of Rome. Our most important issue will be the F-35,” Erdogan was quoted as saying by the Associated Press.

The United States had removed Turkey, a NATO member country, from the international program that produces the F-35 jets in 2019 over Ankara’s decision to buy Russia’s advanced S-400 surface-to-air missile defense system. Washington says the Russian system compromises the F-35s’ security.

Erdogan has previously said that his government is seeking to recover a $1.4 billion payment that the country made before it was expelled from the F-35 program and that the United States has proposed selling F-16 fighter jets to Turkey to make up for the payment.

“We have a 1.4 billion payment regarding the F-35s. We need to discuss how the repayment plan will be,” Erdogan said.

Erdogan had previously said he planned to meet with Biden during a G-20 meeting in Rome.

Erdogan’s comments came days after the Turkish leader stepped back from a threat to expel the ambassadors of the United States and nine other Western nations over their support for a jailed activist, defusing a potential diplomatic crisis.

The envoys last week called for the release of philanthropist Osman Kavala, who has been in a Turkish prison for four years awaiting trial on charges that many view as unfounded.

The crisis was averted after the embassies stated that they comply with Article 41 of the Vienna Convention, which outlines diplomats’ duties to respect the laws of the host state and not to interfere in internal affairs.

Erdogan denied that he had taken a step back in the crisis.

“I am on the offensive. There is no back-stepping in my book,” he said.