Turkish President Recep Tayyip Erdogan is due to visit Qatar this week with a request to buy 24 second-hand Eurofighter Typhoon aircraft to modernise his country’s air force.

The UK, a member of the Eurofighter consortium, has been facilitating talks to transfer Tranche 3A aircraft from Qatar to its close military ally Turkey, alongside Ankara’s request to buy 16 new Tranche 4 aircraft as part of a multi-billion-dollar deal, according to people familiar with the matter.

The deal has not been finalized, and discussions on technical arrangements are ongoing, the people said.

Turkey, a NATO member, is the world’s second-largest operator of US F-16s and has never used other foreign models. It is seeking to deepen defence ties with Europe and hopes to start the first deliveries of Eurofighters as early as next year, with new F-16s unlikely to arrive before 2030, said the sources, who spoke on condition of anonymity. Almost all European countries have increased their defense spending this year as they face an aggressive Russia.

Erdogan is scheduled to visit Doha as part of a regional tour that includes Kuwait and Oman this week. Turkey’s Defense Ministry declined to comment. The U.K. Defense Ministry and the Qatari government did not immediately respond to requests for comment.