British engine maker Rolls-Royce Holdings Plc said on Sunday it had scaled back efforts to join a Turkish program to build a new fighter jet with Turkey’s Kale Group.

Talks between Kale and Rolls-Royce ran into problems last year because of a dispute about the sharing of intellectual property and the involvement of a Qatari-Turkish company, the company said.

Rolls-Royce has abandoned its attempts to win the bid for the fifth-generation fighter aircraft after failing to find a compromise, the engine maker added.

The Financial Times first reported the story and a Rolls-Royce spokesman later confirmed the development to Reuters.

Kale Group did not immediately reply to a request for comment.

In 2017, Kale Group said it would set up a joint venture with Rolls-Royce to develop aircraft engines after the UK and Turkey signed a defense deal worth more than 100 million pounds ($133 million) to develop Turkish fighter jets.

Last year, Turkish Defence Industry Director Ismail Demir said the door remained open for international engine makers to get involved in Turkey’s TF-X national fighter jet project.