Deadly Israeli attacks that blew up Hezbollah radios and pagers crossed all red lines, the leader of the heavily armed Iran-backed Lebanese movement said on Thursday, as the United States called for restraint and urgent de-escalation.

The Hezbollah leader, Hassan Nasrallah, did not say how his group would respond to attacks on hand-held devices, which killed dozens when pagers and walkie-talkies exploded.