It his hard to imagine a worse neighbor. Wagner Group chief Yevgeny Prigozhin is famously cruel. He commands a battle-hardened force of thousands. And he does not care for rules.

But it looks like the long-suffering people of Belarus will be stuck living with the mercenary boss turned mutineer thanks to a deal granting him safe passage in return for calling off his march on Moscow.

The agreement, brokered by Belarusian dictator Alexander Lukashenko, seems to have averted a leadership crisis in Russia but may be the start of a new mess if Prigozhin rebuilds in this Russian vassal state.

Although much about his stay remains unclear, Prigozhin’s arrival Tuesday is a stark reminder that Russia’s chaos is unlikely to stay in Russia and could seep westward, creating instability in Belarus, new challenges for Ukraine and questions for the rest of Europe — just as many warned.

“The primary victim of this situation is the Belarusian people,” said Franak Viacorka, the chief adviser to the exiled Belarusian opposition leader Svetlana Tikhanovskaya.

Prigozhin “will come in with criminals; he will bring the culture of violence,” he continued. “It will create instability in the country and at its borders, too.”

It is still unclear what, exactly, was agreed between Prigozhin, Lukashenko and Russian President Vladimir Putin. Over the weekend, Kremlin spokesman Dmitry Peskov outlined a deal under which Prigozhin halted his march on the Russian capital in return for passage to Belarus and the dropping of charges — but many wonder whether there is more to the arrangement.

It remains to be seen whether Prigozhin will live in Belarus solo or with legions of loyal, veteran troops. “For me, the question is, is it one Prigozhin, or if it’s 25,000 Wagner fighters, or at least a good chunk of them, too?” said Michal Baranowski, the managing director of Warsaw-based GMF East, part of the German Marshall Fund think tank.

“If he’s moved to retirement and Wagner will be integrated into Russian forces, that is a good scenario,” Baranowski continued. “If they get reconstituted in Belarus and provide advice to Lukashenko, strengthen Belarusian forces, or God forbid, create military bases, that is big for us, for the Baltics, for Ukraine.”

On Tuesday, Lukashenko expressed interest in learning from Wagner fighters fresh from combat. “Listen, they are on the front lines,” he said in a meeting, according to the state news agency. “They went through this. They will tell you about weapons — which worked well, which did not. And tactics, and weapons, and how to attack, how to defend. It’s priceless.”

“There is no need to be afraid of them,” he added.

And yet, for a nation that lives in the shadows of both Lukashenko and his patron, Putin, the arrival of another strongman seems to have few upsides.

To begin, there is no guarantee that Lukashenko is in a position to control a man who managed to march a column nearly to Moscow.

Recent years have not been easy on the Belarusian dictator. When he faced a popular uprising in 2020, one friend came to his aid: Putin. To thank him, Lukashenko has allowed the Russian leader to use his country as a base for weapons and troops and now as a dumping ground for an unwanted warlord.

The move, according to Viacorka, may accelerate the “militarization” of Belarus. “For those who fight for democracy, it’s become more difficult,” he said.

The possibility of a Prigozhin base in Belarus also is problematic for Ukraine.

In the leadup to Russia’s full-scale invasion, Belarus became a staging point for the Russian assault. Now, there are concerns that Prigozhin could be in a position to attack Ukraine from the north.

European Union countries also are watching what is happening in Belarus.

E.U. leaders have long been split on how to respond to Belarus’s transformation into a Russian client state, with some countries calling for the bloc to try to lure Lukashenko away from Putin and others hoping to take a tougher line with Minsk.

In a recent speech, for instance, French President Emmanuel Macron said the West had pushed Belarus toward Russia — a remark that drew eye rolls from Belarusian activists and Eastern European officials.

In recent days, Belarus’s E.U. neighbors have reiterated their concern about unrest in Belarus spilling across their borders.

On Sunday, Lithuanian President Gitanas Nauseda said Belarus was becoming a haven for “war criminals.”

“The control of NATO borders and the defense of its eastern flank is most important!” he tweeted.

Baranowski of the German Marshall Fund said the impact of the Prigozhin episode on Europe depends entirely on what happens to Prigozhin’s troops. “If Wagner is reconstituted in Belarus, this would be a new military reality to which NATO would have to react,” he said.

“But small chunk of them, I am not as concerned,” he added, “because NATO has been preparing.”

The Washington Post’s Mary Ilyushina in Riga, Latvia, contributed to this report.

previous coverage

• Prigozhin’s rebellion raises questions about Wagner’s African footprint
• Kremlin disarray means opportunity for Ukraine — if the West acts
• Belarusian dictator Lukashenko's unlikely cameo as mediator with Wagner
• The road to Moscow: A timeline of Wagner’s rebellion
• US spies learned in mid-June Prigozhin was plotting Russia uprising