By Thomas Grove

Belarusian President Alexander Lukashenko has become the target of international outrage following his decision to employ a war plane to divert a Ryanair flight to his country's capital of Minsk to detain an opposition journalist and activiston May 23.

Days after the incident he spoke to parliamentarians to publicly defend his grounding of the plane and accuse the West of meddling in the country's affairs.

The European Union has agreed on fresh sanctions against Belarus, promising to bar the country's airline Belavia from its airspace. The move shows Belarus, which has started a crackdown against the opposition at home, is willing to track exiled activists down as well.

What happened and why did Belarus divert a Ryanair flight?

While flying over Belarusian airspace, pilots on Ryanair Flight 4978 received a warning from air-traffic controllers that there was a potential security threat on board, and a MiG-29 was sent to escort the Boeing 737-800 to the Belarusian capital. Minutes before the plane was meant to cross into Lithuanian airspace, the plane made a sharp right and landed at the Minsk airport.

A transcript released by the Belarusian aviation agency, which wasn't independently by The Wall Street Journal, showed that a Ryanair pilot repeatedly asked for clarification over ground controller's request that the plane reroute to Minsk.

No security threat was found on board. The plane, the passengers and their luggage were searched for several hours. When the plane took off, Belarusian passenger Roman Protasevich, an opposition activist who had carried out his opposition activities against President Alexander Lukashenko from exile, wasn't on board. Neither was his Russian girlfriend, who was traveling with him. Opposition activists say he was detained by security forces at the airport.

To justify the move, the Belarus Transport Ministry said it received an email from Hamas, claiming it had put a bomb on board the plane.

Mr. Lukashenko told parliamentarians on Wednesday that his government had acted responsibly on information that a bomb was on board the plane. He also said pressure from the West was an attempt to meddle in Belarus' affairs.

Who is Roman Protasevich?

Mr. Protasevich is a longtime opposition activist who left Belarus in 2019, fearing arrest. He has lived the past several years mostly in neighboring Lithuania, which has become an outspoken opponent of Mr. Lukashenko's regime. The president's harsh tactics against the opposition have led some to call him Europe's last dictator. It was from abroad that Mr. Protasevich led coverage for the opposition Telegram channel Nexta of the 2020 Belarusian presidential elections and protests that followed. Many Belarusians believed the vote was falsified and accused Mr. Lukashenko of stealing the vote, causing a nationwide protest movement against him.

Why did Belarus President Lukashenko want to arrest Mr. Protasevich?

In a country where the media has largely been muzzled by the state, Nexta videos brought Belarusians unflinching coverage of the protests, including some of the worst police violence against protesters. Under Mr. Protasevich's editorship, Nexta grew to at least 1.5 million subscribers and helped fuel the protest movement.

Last year, Mr. Protasevich was accused of organizing mass riots and other crimes. Belarusian security forces, which go by their Soviet-era title, the KGB, put him on a list of terrorists for having incited mass unrest. He says the allegations are being used as political pressure against him.

How has Ryanair reacted?

Ryanair Holdings PLC's chief executive, Michael O'Leary, has called the incident a case of state-sponsored hijacking, and says he believes members of the Belarusian KGB were on the flight, tailing Mr. Protasevich. "We believe there were some KGB agents unloaded at the airport as well," he told Ireland's Newstalk radio channel.

Mr. O'Leary said the airline was debriefing the crew and that the incident was frightening for passengers and crew, saying they were held under armed guard and had their bags searched.

Ryanair, a budget carrier and one of Europe's largest airlines, said it was assessing whether or not to continue to fly over Belarus airspace and was awaiting guidance from European aviation regulators. Two other airlines, Wizz Air Holdings PLC and AS Air Baltic Corp., both said they would no longer fly over the country.

What happens next?

Mr. Lukashenko is expected to meet Mr. Putin later this week in what will be Moscow's clearest signal of support to Belarus since the incident. The meeting stands in contrast to the fresh sanctions slapped on Belarus by EU leaders. In a meeting on Monday, they called on European-based airlines to avoid Belarusian airspace and promised to work to ban Belarusian airlines from the bloc's airspace and airports.

Lithuania has already shut its airspace to Belarus. U.K. Foreign Secretary Dominic Raab earlier said Britain was suspending the operating permit of Belarus's national airline and advising U.K. airlines to avoid the former Soviet country's airspace.

The move could have severe implications for revenue of the state airline, which has flights across Europe.

The European Council also called for the release of Mr. Protasevich and his girlfriend, who was detained with him.

U.S. Secretary of State Antony Blinken has likewise condemned the actions, saying Washington demands an international investigation and is "coordinating with our partners on next steps."

Write to Thomas Grove at thomas.grove@wsj.com

(END) Dow Jones Newswires

05-26-21 1327ET