Pakistan, March 11 -- Lebanon's Hezbollah is applying lessons from its last war with Israel as it braces for a possible full-scale Israeli invasion and protracted conflict, returning to its roots in guerrilla warfare in south Lebanon, four Lebanese sources said.

Operating in small units, fighters from the Iran-backed group are avoiding the use of communication devices that could be at risk of Israeli tapping, and are rationing the use of key anti-tank rockets as they engage Israeli troops, said the sources, who are familiar with Hezbollah military activities.

Some 15 months since Israel pounded Hezbollah in their last war, the group sparked a new Israeli offensive last week by opening fire to avenge the killing of Supreme Leader Ayatollah...