US President Donald Trump has approved a defence budget law delaying the delivery of F-35 fighter jets to Turkey.

The $716 billion “National Defense Authorization Act” for Fiscal Year 2019 (NDAA) prohibits the sale of F-35 aircraft to Turkey for 90 days until the Pentagon produces a report on the risks entailed by the fellow NATO member-country’s purchase of the Russian S-400 missile defence system.

Turkey order 30 F35s and received its first pair of a projected 100 aircraft in June. The jets remain in the US while their Turkish pilots receive training. Delivery will not take place before September 2019.