The leader of Hezbollah on Tuesday pledged a "strong and effective" response to the killing of its military commander by Israel last week and said it would act either alone or with its regional allies.
Hassan Nasrallah said Hezbollah would wait for the right moment to respond but did not hint on its form or timing. All international attempts at persuading Hezbollah not to retaliate were futile, he said.
"Whatever the consequences, the resistance will not let these Israeli attacks pass by," he said in a televised address to mark one week since the assassination of Hezbollah military commander Fuad Shukr in Beirut.
"Our response, God willing, will be strong, effective and impactful."
Members and supporters of Hezbollah gathered to watch the speech in a southern suburb of Beirut. Just before his speech began, Israeli warplanes swooped low over the Lebanese capital, setting off a series of sonic booms that rattled windows across the city and sent people ducking for cover.
There was no comment from the Israeli military.
Concern is rising that the Middle East could tip into full-blown war following Hezbollah's vows to avenge Shukr's killing, and Iran's anger over the assassination in Tehran last week of the head of Palestinian group Hamas.
The strike that killed Shukr on July 30 was the second time Israel had struck the southern suburbs in 10 months of hostilities between Hezbollah and Israeli that are taking place in parallel with the war in Gaza between Israel and the Palestinian group Hamas.
Hezbollah earlier on Tuesday said it launched a swarm of attack drones at two military sites near Acre in northern Israel and attacked an Israeli military vehicle in another location.
The Israeli military said a number of hostile drones were identified crossing from Lebanon and one was intercepted.
Israeli medical officials said seven people were evacuated to hospital, to the south of the coastal city of Nahariya, one in critical condition.
The Israeli military said an initial investigation indicated the injuries were caused by an interceptor that "missed the target and hit the ground, injuring several civilians".
Reuters journalists saw one impact site near a bus stop on a main road outside Nahariya.
The Israeli military said in a statement sirens sounded around Acre, but that turned out to be a false alarm. It said its air force struck two Hezbollah facilities in south Lebanon.
Earlier on Tuesday, four Hezbollah fighters were killed in a strike on a home in the Lebanese town of Mayfadoun, nearly 30 km (19 miles) north of the border, medics and a security source said.
Meanwhile, the Lebanese caretaker government is trying to prevent a Hezbollah response against Israel that could start a wider war, Lebanon's foreign minister Abdallah Bou Habib said on Tuesday during a press conference with his Egyptian counterpart.
