By Laila Bassam and Maya Gebeily BEIRUT/JERUSALEM (Reuters) -Israeli warplanes carried out late on Thursday their most intense strikes on southern Lebanon in nearly a year of war, heightening the conflict between Israel and Lebanese armed group Hezbollah amid calls for restraint.

The attack came as the militant group’s leader said two days of pager and walkie-talkie explosions amounted to a declaration of war.

U.S. officials say Israel warned U.S. Defense Secretary Lloyd Austin in a call Tuesday that a military operation was going to take place in Lebanon.