Why is Belarus amassing troops along its border with Ukraine?

Ukraine has asked Belarus to pull back forces that it has sent to their border amid rising military tensions between the neighbours following the Ukrainian incursion into Russia’s Kursk region.
The latest warning from Ukraine follows two weeks of sharpening rhetoric, accusations and countercharges levelled by Kyiv and Minsk at each other. This, at a time when Russia — which counts Belarus as its most steadfast ally — has threatened a firm response to Ukraine’s Kursk offensive.
So what is really going on between Ukraine and Belarus, and could their border emerge as the latest theatre for Russian President Vladimir Putin’s war?
Late on Sunday, Ukraine’s Ministry of Foreign Affairs urged Belarus to withdraw a build-up of its troops from their border and to “stop unfriendly actions”.
It cited intelligence to accuse Belarus of “concentrating a significant number of personnel, including Special Operations Forces, weapons and military equipment” in the Gomel region near Ukraine’s northern border “under the guise of exercises”.
“We warn Belarusian officials not to make tragic mistakes for their country under Moscow’s pressure, and we urge its armed forces to cease unfriendly actions and withdraw forces away from Ukraine’s state border to a distance greater than the firing range of Belarus’s systems,” the Foreign Ministry said in its statement.
Ukraine said Belarusian troops, as well as mercenaries from the Russian Wagner Group, had lined up near the border. The two countries share a 1,084km (674-mile) long border.
“We warn that in case of a violation of Ukraine’s state border by Belarus, our state will take all necessary measures to exercise the right to self-defence guaranteed by the UN Charter,” the Foreign Ministry said. “Consequently, all troop concentrations, military facilities, and supply routes in Belarus will become legitimate targets for the Armed Forces of Ukraine.”
It also pointed out that the region where Belarusian troops had gathered was close to the disaster-hit Chornobyl nuclear power plant, and said any military exercises conducted there posed a “threat to the national security of Ukraine”.
Last week, Belarusian President Alexander Lukashenko announced that the country had moved around a third of its forces to the border with Ukraine.
But Lukashenko blamed Ukraine for the sharp escalation in tensions.
He accused Ukraine of aggressive policies and of sending more than 120,000 soldiers to its border with Belarus on August 18. The next day, Belarus announced that it sent aircraft, air defence forces and armoury to the Ukraine border.
Belarus has accused Ukraine of violating its airspace during its attack on Russia’s Kursk region on August 6. Minsk first declared the movement of soldiers towards the border with Ukraine as an act of self-defence on August 10.
Defence Minister Viktor Khrenin said Belarus was “ready for retaliatory action” if Ukrainian soldiers entered its territory.
But Ukraine has rejected the Belarusian allegations. It denied Lukashenko’s claim that Kyiv had sent 120,000 soldiers to the border. On Sunday, the Ukrainian Foreign Ministry said it “has never taken and is not going to take any unfriendly actions against the Belarusian people”.
Belarus has maintained close political and economic relations with Russia since its independence from the Soviet Union in 1991.
Lukashenko is a firm ally of Putin and his country has stood by Russia over the course of its war with Ukraine. In March 2022, soon after Russia launched its full-fledged invasion of Ukraine, Belarus evacuated its embassy in Kyiv as a show of support for Moscow.
Belarus has also permitted Russia to station its troops on its territory, which allows Moscow to use its ally’s land as a launchpad to attack Ukraine from the north.
Ukraine’s Western allies, especially the United States, have imposed a slew of penalties on Belarus over its support for Russia’s war — including financial sanctions, export controls, airspace restrictions and visa restrictions on officials.
Yet, until now, Belarus has steered clear of actually engaging in military conflict with Ukraine — and the current troop build-up along their border raises the spectre of that changing.
The Kursk incursion has embarrassed Russia, which in turn has sought to distract from that setback, according to Mathieu Boulegue, a consulting fellow at the London-based Chatham House think tank.
“I think what we see so far is Russian forces and Russian PMCs launching counterattacks from the territory of Belarus as a distraction from the Kursk incursion,” he told Al Jazeera, referring to private military companies (PMCs) such as Wagner.
“But I doubt Belarus will send its own troops to war,” he added.
“Lukashenko’s regime is a complete vassal state to the Kremlin, but it is more valuable for Russia to keep it as a launchpad for military operations than engulf it into the war,” Boulegue said. “The moment they do that, it creates much more instability than necessary, with the risk of losing regime stability in Minsk, and forcing a hard international response.”