Europe has three to five years to prepare for Russia becoming a serious military threat on NATO’s eastern flank, says the Prime Minister of Estonia, Kaya Kallas. Highlighting feelings of instability, Kaya Kallas became the first NATO leader to suggest that Russia was behind the recent disruptions in GPS navigation in the southern part of the Baltic Sea. However, she noted that this disruption did not seem to be intentionally targeted at NATO members. Concerns are growing within the North Atlantic Alliance about how long its members will have to prepare for the potential deployment of Russian t…