High stakes: National security community braces for nuclear brinkmanship if summit fails

All signs may point to a successful and historic summit between President Trump and Kim Jong-un, but the stakes are so high that the U.S. national security community is braced for the possibility of a rapid spiral toward nuclear brinkmanship if the talks between the two men turn sour.

With the North Korean side notorious for bizarre antics and sudden walkouts from diplomatic meetings, it remains anyone’s guess how Tuesday’s face-to-face will ultimately play out — even as most analysts agree that Mr. Trump and Mr. Kim are both driven...