The Russian army has launches a tank biathlon, a competition invented by Russia's Defence Ministry, and invited the US armed forces to take part.
Russian-made T-72 tanks have been racing around a 20-kilometre or 13 mile track trying to hit five firing targets in the competition.
For every miss there was a penalty loop of 500 metres.
"Spectators who come to visit us can watch not just a show, but a competition between real men on real tanks," a spokesman said.
So far, only tanks from four countries, including the former Soviet republics of Armenia and Kazakhstan, have taken part in the competition.
But next year's event will include tanks from Italy and Germany, Russia's defence minister said.
The tank biathlon is due to finish on Saturday.