NATO expects to increase its military presence in the Baltic States and Poland in case Russia leaves its troops in Belarus after planned military exercises, Rob Bauer, head of the military committee of the alliance said, Reuters reported.

According to him, further deployments of NATO allies are possible.

"It very much depends, of course, on whether the Russian troops in Belarus remain in Belarus," he said.

"If you look at the buildup of the forces, Russia could be able to actually have sufficient forces for a serious invasion … by the end of this month," said Bauer. "Whether they do that, whether they have the true intention or not, we don't know."

The most recent deployments at the Belarus border included field hospitals and other auxiliary units needed to support a military assault, Bauer said.

"If you're really considering an invasion, you actually need more than the fighting forces. And that is something we also see more and more gathered along both the borders with Ukraine and Belarus with Ukraine. That in itself is very concerning", he said.