Hezbollah members take part in a military exercise during a media tour in Aaramta, Lebanon, May 21, 2023.

Explosions rocked Beirut on Friday and Saturday as Israeli attacks first targeted Hezbollah leader Hassan Nasrallah and then several buildings in the Lebanese capital where the militant group’s rockets are said to be stored.

Although this is a recent escalation in fighting, here’s what you should know about it decades-long conflict:

Israeli invasion: Israel captured almost half of Lebanon’s territory when its forces invaded in 1982. This included Beirut, where Israeli forces, along with right-wing Christian Lebanese militias allied with Israel, laid siege to the western part of the capital to drive out Palestinian militants.

According to reports and an Israeli investigation into a massacre at a refugee camp in Beirut, the Israeli operation resulted in the deaths of over 17,000 people. The investigation indirectly blamed Israel for the massacre of Christian Lebanese fighters.

The rise of Hezbollah: As droves of Palestinian fighters left Lebanon, an Iranian-trained group of Shiite Islamist militants burst onto the scene. In 1983, two suicide bombers affiliated with this faction attacked a U.S. Marine barracks in Beirut, killing nearly 300 U.S. and French soldiers and civilians.

A year later, Iran-allied militants bombed the U.S. Embassy in Beirut, killing 23 people. In 1985, these militants banded together to form a newly formed organization: Hezbollah.

Support for Gaza: Hezbollah is part of a larger Iran-led alliance of militant groups in Yemen, Syria, Gaza and Iraq that has increasingly clashed with Israel and its allies since the start of the war with Hamas – and has vowed to fight until the end of the war to carry on.

Killing the main leader: Tensions escalated when Israel said it had killed Hezbollah’s top military commander, Fu’ad Shukr, in an attack on Beirut in July. In retaliation, Hezbollah fired hundreds of drones and rockets into Israel.

Displaced residents: The increase in cross-border fighting has forced people from their homes in both Israel and Lebanon. Israel made it its war goal this month to send tens of thousands of residents of northern Israel back to their homes near the border. Lebanon has registered more than 100,000 displaced people, but authorities said the actual number was likely much higher.