U.S. military officers observed joint war games between Russia and Belarus on Monday and were told by Belarusian Defense Minister Viktor Khrenin that they could look at "whatever is of interest for you."
Russia and Belarus began the "Zapad-2025" exercise at training grounds in both countries on Friday at a time of heightened tension with NATO, two days after Poland shot down Russian drones that crossed into its airspace.
The attendance of the Americans at a training ground in Belarus was presented by the country's defense ministry as a surprise.
"Who would have thought how the morning of another day of the Zapad-2025 exercise would begin?" it said in a statement noting their presence among representatives from 23 countries including two other NATO member states - Turkey and Hungary.
The ministry released video showing two uniformed U.S. officers thanking Khrenin for the invitation and shaking his hand.
"We will show whatever is of interest for you. Whatever you want. You can go there and see, talk to people," the minister told the Americans, who declined to speak to reporters.
The presence of the U.S. officers is the latest sign of warming ties between Washington and Belarus, a close Russian ally that allowed Moscow to use its territory to send tens of thousands of troops into Ukraine in February 2022.
John Coale, a Trump representative, was in Minsk last week for talks with Belarusian leader Alexander Lukashenko, who agreed to release 52 prisoners from his jails, including journalists and political opponents.
The U.S. granted sanctions relief to Belarus's national airline Belavia in return, allowing it to service and buy components for its fleet, which includes Boeing aircraft. Trump wants to reopen the U.S. embassy in Belarus in the near future, normalize ties, and revive the economic and trade relationship, Coale said.
Trump, who has been trying to broker an end to the war in Ukraine, is cultivating closer ties with Lukashenko, who regularly holds talks with Putin. Last week Trump sent Lukashenko a friendly hand-signed letter via Coale.