Lebanon's Hezbollah said it targeted Israeli military positions in the disputed Shebaa Farms on Sunday, saying it was acting «in solidarity» with the Palestinian people after an unprecedented attack by Hamas gunmen from Gaza into Israel.
Israel responded with barrages of artillery into southern Lebanon. No casualties have been reported.
Backed by Iran, the Shi'ite group has risen from a shadowy faction established during Lebanon's 1975-90 civil war to a heavily armed force with big sway over the Lebanese state.
Governments including the United States deem it a terrorist organisation.
Origins
Iran's Revolutionary Guards founded Hezbollah in 1982 to export its Islamic Revolution and fight Israeli forces that had invaded Lebanon. Sharing Tehran's Shi'ite Islamist ideology, Hezbollah recruited among Lebanese Shi'ite Muslims.
Military Power
Hezbollah kept its weapons at the end of the civil war to fight Israeli forces occupying the predominantly Shi'ite south.
Years of guerrilla warfare led Israel to withdraw in 2000.
Hezbollah demonstrated its military advances in 2006 during a five-week war with Israel, which erupted after it crossed into Israel, kidnapping two soldiers and killing others. The war killed 1,200 people in Lebanon, mostly civilians, and 158 Israelis, mostly soldiers.
Hezbollah fired thousands of rockets into Israel.
Its military power grew after deploying into Syria in 2012 to help President Bashar al-Assad fight mostly Sunni rebels.
Hezbollah boasts precision rockets and says it can hit all parts of Israel. In 2021, Hezbollah leader Sayyed Hassan Nasrallah said the group had 100,000 fighters.
Iran gives Hezbollah weapons and money.