RIGA, Latvia — An airplane flying between two European Union capitals was supposed to be a safe haven from the long arm of Belarusian President Alexander Lukashenko. But after a prominent opposition journalist was arrested when his Ryanair plane was forced to land in Minsk, other dissidents say they understand the message: They cannot consider themselves safe anywhere.

The chill has been felt especially in Vilnius, Lithuania, the hub for self-exiled Belarusian opposition figures — and where the detained journalist, Roman Protasevich, had been living before his ill-fated flight from Athens.

In Vilnius, just half an hour from the border with Belarus, dissidents are able to stay close to their nation. But they also worry about being spirited home by Lukashenko’s agents.

“We’re trying to prevent the situation where someone leaves our office and gets put into the trunk of a car of the Belarus embassy, with diplomatic plates,” said Franak Viacorka, an adviser to opposition leader Svetlana Tikhanovskaya.

Enemies of the Kremlin have long looked to the Baltics and elsewhere in Europe as places where they could take refuge — but had to remain vigilant. In 2018, former Russian spy Sergei Skripal was poisoned Salisbury, England, with what British authorities said was a nerve agent deployed by Russian operatives. The following year, Zelimkhan Khangoshvili, an ethnic Chechen Georgian who had helped identify Russian spies, was killed in Berlin. German prosecutors accused the Russian government of ordering an execution.

But whereas the Kremlin has been known to reach deep into Europe to menace its opponents, Belarus is a small country, with resources far more limited than Russia’s.

“The situation with Roman was a wake-up call for us, to the Western community, to world leaders” about how far Lukashenko will go to grab his critics, said Viacorka, who fled to Vilnius last year with Tikhanovskaya, after the opposition leader lost a disputed presidential election. Lukashenko’s administration requested Tikhanovskaya’s extradition in March.

She told reporters after the plane incident that she had been on the same fight from Athens the previous week. “I could be in the place of Roman right now,” she said.

Tikhanovskaya has continued to travel, meeting with Estonian leaders on Monday in their capital, Tallinn. Last week, she briefly visited the Netherlands, where she met with Dutch Prime Minister Mark Rutte. Flights from Vilnius to Amsterdam stay in E.U. airspace.

Baltic leaders say Protasevich’s capture was a message to other Belarusians abroad. Lithuanian President Gitanas Nauseda told The Washington Post he read the move as: “Guys, look, we will catch you everywhere, no matter where you are — in the air, under the water or hiding in the forest. We will catch you. And even if you fly from one capital of the European Union to another capital of the European Union, we are able to catch you, too.”

Nauseda said he wanted to make the price for Lukashenko as high as possible, to deter him from trying something like that again.

Meanwhile, European diplomats are warning self-exiled dissidents to be cautious.

“You’re a public person, you know, and you’re fighting a big country. You have to be careful of what they do to you,” said Lithuanian Foreign Minister Gabrielius Landsbergis.

Lithuania is “a safe, nice, green, wonderful country. But we have to understand that even though it’s a NATO country, intelligence security officers from the unfriendly countries are active here,” he said, adding that Lithuanian intelligence agencies keep a constant eye on foreign threats to their temporary residents.

“Anybody who criticizes Putin’s regime or Lukashenko’s regime can have a problem,” said Evgeniya Chirikova, a Russian environmental campaigner who was a thorn in the Kremlin’s side until she left for Estonia in 2015. “And, at this moment, of course, Lukashenko organized a new method of pressure. Of course, it’s a really unsafe situation.”

Leaders in Europe and the United States are seeking to punish Lukashenko’s move with sanctions. But Putin has offered his support, meeting with Lukashenko last week, posing with him for photos on a boat, and promising to release $500 million from a previously agreed loan.

With the Kremlin’s continued backing, the Belarusian leader may not be deterred by the Western measures, at least for now.

European leaders say they know their effort to deal a blow to Lukashenko will drive him closer to Russia and could even force him to make concessions to Putin, who has long wanted tight political integration with Belarus to ensure that it stays firmly aligned with Moscow. But they hope that if Belarus needs ever more support from the Kremlin to stay afloat, Putin may eventually tire of Lukashenko and decide to pull the plug.

If sanctions “isolate Lukashenko from Europe, the only alternative for Lukashenko will be to get even closer to Russia,” said Nauseda, the Lithuanian president. “This is a secondary consequence of what is happening right now. Belarus is just a target for Russia to swallow, and Russia is trying to implement the ultimate goal: to make these two states into one state.”

Some top Putin allies said they were watching Minsk with admiration last week — a worrisome sign, perhaps, for Russians abroad.

“I never thought that I would envy Belarus in any way. But now I somehow envy it,” Margarita Simonyan, editor of RT, a Russian state-run news network, wrote on Twitter after the plane was forced down. Lukashenko “performed beautifully.”