By the time President Donald Trump was milling about his golf club in New Jersey on Friday evening, the planes were about to be in the air. To onlookers at the club, Trump showed little anxiety about his decision to authorize airstrikes on three Iranian nuclear facilities that could have profound ramifications both on US national security and his own presidential legacy.

The world grappled Sunday with the enormous implications after the United States inserted itself into Israel’s war against Iran with an attack that raised urgent questions about what remained of