On 27 November 1919 the Treaty of Neuilly-sur-Seine was signed. In accordance with the treaty the Kingdom of Bulgaria was banned from operating military aircraft under any form for the next 20 years. All Bulgarian airplanes, balloons, aviation equipment, weaponry and ammunition were to be destroyed under Allied control and all personnel demobilised. Under the terms of the treaty any aircraft procured for civilian purposes had to be bought from the countries on the winning side. The combined engine power for any airplane (including multi-engined ones) was not to exceed 180 hp. In addition, the Bulgarian airspace was to be controlled by the allies and used according to the victorious countries' interests.