Pakistan, June 10 -- The latest exchange between Israel and Iran lasted barely long enough to remind the region how little separates diplomacy from escalation. A ceasefire that appeared stable one day looked vulnerable the next, until President Donald Trump intervened publicly and both sides stepped back. Yet even as direct fire subsided, Israeli aircraft continued to strike targets in Lebanon as Iran warned that further attacks on Hezbollah could provoke a response.

This is not simply another episode in a conflict that has already produced too many. Washington appears to be pursuing an understanding with Tehran on the assumption that the Iran file can be managed separately from the Lebanon file. The events of the past week suggest that ...