A top U.S. official visiting the Lebanese capital on Thursday discouraged Tehran-backed armed group Hezbollah from intervening in the war between Iran and Israel, saying it would be a "very bad decision".

Hezbollah, Iran’s most powerful regional ally, has signaled privately that it does not intend to attack Israel, but Lebanon’s military has bolstered its presence in the country’s south to prevent rocket fire.

One of Israel’s most feared scenarios has long been that Iran would unleash an attack on it in coordination with its powerful network of proxy militias.