Such scenarios might include a cyberattack or a “small-scale land incursion,” including the possibility of sending unmarked troops into a NATO member state. Testing Article 5Article 5 of the North Atlantic Treaty, which governs NATO, states that an attack on one NATO member is seen as an attack on all. Should Russia invade a NATO member state, it would be seen, under Article 5, as an attack on the entire alliance, the United States included. “The question mark is how the United States would respond in that case,” Conley told the Journal of the possibility that Russia could further test NATO states. That could pose an even bigger problem should Putin attack a NATO ally in the near future.