Belarus's authoritarian leader, Alyaksandr Lukashenka, said that Russia and Belarus will deploy a joint military task force, claiming without evidence that Ukraine is planning to attack his country.
"I've said already that today Ukraine is not just discussing but planning strikes on the territory of Belarus," state news agency Belta quoted Lukashenka as saying during a meeting with security officials.
"We have agreed to deploy a regional grouping of the Russian Federation and the Republic of Belarus," he added, without specifying where the troops would be deployed.
He said the formation of these troops started two days ago, coinciding with an explosion on a bridge linking Crimea to Russia that Moscow blamed on Ukraine.
Belarus "must have plans in advance to counter all kinds of scoundrels who are trying to drag us into a fight," Lukashenka said.
"There should be no war on the territory of Belarus," he added.
Belarus relies financially and politically on its key ally Russia.
Russian forces used Belarus as a staging post for their February 24 invasion of Ukraine, sending troops and equipment into northern Ukraine from bases inside Belarus.