BRUSSELS - NATO on Tuesday warned Russia to stop an "escalatory" pattern of airspace violations along its eastern flank, after the alliance held urgent talks about a jet incursion over Estonia last week. In response to the drone raid in Poland, NATO announced it was bolstering its eastern defenses to help to counter the threat from Moscow. Besides Poland and Romania, other eastern flank countries including Romania, Lithuania, Latvia and Finland have seen recent violations of their airspace. The spike in tensions has spurred fears that the Russia war in Ukraine could be spilling across NATO's border. Under NATO's Article 4, any member can call emergency discussions when it feels its "territorial integrity, political independence or security" are at risk.