Russian forces poured into Ukraine from three directions. From the east and south, they entered from Russia itself, or Russian-claimed territory. But from the north, the Russian army came through Belarus.

Russian troops and military hardware have been trickling into Belarus since Jan. 17, for what were called joint military drills. By February, NATO officials estimated that Russian forces in the country numbered as high as 30,000. Now some officials are warning that the troops may never leave.

Before the invasion, Putin claimed Russian forces in Belarus were there for coordinated military drills, and then maintained his troops in Ukraine were there for a “special military exercise.” The reality, experts tell Fortune, is that Putin is occupying more and more areas of Eastern Europe.