Eastern European state Belarus made more enemies than it already has on Sunday, after intercepting a Ryanair flight carrying dissident journalist Roman Protasevich and his girlfriend Sofia Sapega.

As the United Nations' International Civil Aviation Organisation (ICAO) probes the incident, The Straits Times looks at the gravity of Belarus' actions and the impact of any potential sanctions.

Q: Did Belarus run afoul of international aviation laws?

A: Belarus' strongman President Alexander Lukashenko ordered a fighter jet to intercept the Ryanair plane while it was in his country's airspace and forced it to land in Minsk instead of its original destination of Vilnius in Lithuania.

This coerced landing could contravene the First Freedom of the Air, a core aviation treaty for maintaining international order after World War II that allows planes to fly over other countries without the need to land.

Commercial aircraft can be legally intercepted for safety reasons, such as the bomb threat that the Belarusian authorities claimed to have received from Palestinian militant group Hamas.

But evidence has emerged that the alleged e-mail threat was sent 24 minutes after the plane changed its course. Hamas has also rejected this allegation.

Belarus also risks violating the 1971 Montreal treaty, which outlaws the seizure of aircraft or knowingly communicating false information in a way that endangers aircraft safety.

Q: How have other countries and the aviation authorities responded?

A: The European Union Aviation Safety Agency said it is advising EU airlines and non-EU carriers to avoid Belarus' airways except in emergencies. This, however, is not mandatory.

United States President Joe Biden said on Tuesday that US sanctions against Belarus are in play, but declined to speculate further.

Russia has stood by its ally, forcing at least two EU airlines from France and Austria to cancel their flights to Moscow after the aviation authorities refused permission to change their routes to bypass Belarus.

Q: Can ICAO actually sanction Belarus?

A: In short, no. Although highly regulated at a national level, aviation lacks a global policeman to avoid disputes over sovereignty.

The ICAO, of which Belarus is a member, is the UN body overseeing international aviation standards, and has started a "fact-finding investigation" into Belarus' interception.

But the Montreal agency has no actual regulatory power. It wields clout through its safety and security standards, approved by its 192 member states. Under global rules, neither ICAO nor any nation can close another nation's airspace.

"We wish to remind those who demanded we take punitive action against that country that our agency was never assigned that type of role or capability," ICAO tweeted on Wednesday.

Minsk has rejected charges that it acted illegally.

REUTERS, BLOOMBERG