"If a military aircraft intercepts you and gives you command, you obey". That was the view of one pilot who spoke to the BBC, who said the decision of Belarus to force down a passenger aircraft was "absolutely reckless". Belarus scrambled a fighter jet to divert a Ryanair passenger plane - flying from Greece, bound for Lithuania - to land in Minsk on Sunday, claiming a bomb was on board. None was found. Police then took opposition journalist Roman Protasevich away when the plane landed in the Belarus capital. It was an airport that the pilots did not have on their flight plans. Those within aviation called this a "major diplomatic incident", so serious that those we spoke to cannot remember anything similar. When an aircraft flies through international skies, aircraft have the nationality of the state in which they are registered. In this case, the Ryanair plane is understood to be registered in Poland to "Ryanair Sun", a subsidiary of the Irish airline. When the plane is flying, regardless of its position in the skies, it remains of Polish nationality. "To interfere with an aircraft in flight is a diplomatic incident involving the state of registration," said a senior industry source from a major aviation business. A pilot added that"this is a huge contravention of so many international agreements". The law allowing planes to overfly countries without the need to land is the "First Freedom of the Air" and these freedoms of the air are essential to enable passengers and traffic to move from one country to another around the world. The decision by Belarus to intercept a passenger aircraft in the air and force it to land in a third country breaks this code. It's for this reason the boss of Ryanair, Michael O'Leary, has described the situation as "state sponsored piracy". But Belarus has not signed the International Air Services Transit Agreement, which is what embodies the "First Freedom of the Air" and a list of other codes.