Weeks of Russian incursions into NATO skies have pushed the U.S.-led alliance to the brink of an explosive choice: strike back or stand down.

Why it matters: With peace talks frozen and nuclear threats flying, NATO and Russia are closer to a direct military confrontation than at any point since the Cold War. • President Trump, long reluctant to confront Moscow, stunned allies this week by saying he supports shooting down Russian aircraft if the incursions continue. • The Kremlin's response was a blunt one: shoot down a Russian jet, and war will follow.

The big picture: NATO officials believe Russia is deliberately testing the alliance's defenses — and its political will — with a wave of escalating provocations. • Sept. 9-10: Nearly two dozen Russian drones entered Polish airspace,

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