NEAR BORISOV, Belarus (Reuters) -U.S. military officers observed joint war games between Russia and Belarus on Monday and were told by Belarusian Defence 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 defence ministry as a surprise.