The Iranian government says its missile strikes are over, so long as Israel doesn’t bomb Lebanon. Israel in turn says it will not attack Iran, but insists it will respond if Hezbollah in Lebanon once again fires rockets at northern Israel.

But another Israeli assault on Beirut could collapse the two sides’ fragile truce.

The fragile ceasefire that had largely held between Israel and Iran since April came under renewed strain after both countries exchanged military strikes, raising fears that the…