If I lived on the border, I'd be upset, too. However, this isn't very far from standard Russian way of doing things. They regularly invade air space of various NATO countries, maybe just to test their fighters, maybe to introduce some tension, who knows. The routine is that our fighters escort the intruders back to where they came from. In this case, since the military training was communicated well in advance and the army was expected their aircraft near the border, nobody even bothered. Funnily enough, the last news from Belarus indicate that it might be in fact an accident, not planned action.