The Israel Defense Forces invade and occupies southern Lebanon in Operation Litani.
The 1978 South Lebanon conflict (codenamed Operation Litani by Israel) began after Israel invaded southern Lebanon up to the Litani River in March 1978, in response to the Coastal Road massacre near Tel Aviv by Lebanon-based Palestinian militants. The conflict resulted in the deaths of 1,1002,000 Lebanese and Palestinians, 20 Israelis, and the internal displacement of 100,000 to 250,000 people in Lebanon. The Israel Defense Forces gained a military victory against the Palestine Liberation Organization as the latter was forced to withdraw from southern Lebanon, preventing it from launching attacks on Israel from across its land border with Lebanon. In response to the outbreak of hostilities, the United Nations Security Council adopted Resolution 425 and Resolution 426 on 19 March 1978, which called on Israel to immediately withdraw its troops from Lebanon and established the United Nations Interim Force in Lebanon (UNIFIL).
The Israel Defense Forces (IDF; Hebrew: צְבָא הַהֲגָנָה לְיִשְׂרָאֵל Tsva ha-Hagana le-Yisra'el; lit. 'The Army of Defense for Israel'), commonly referred to by the Hebrew-language acronym Tzahal (צה״ל), are the combined military forces of the State of Israel, consisting of three branches: the Israeli Ground Forces, the Israeli Air Force and the Israeli Navy. It is the sole military wing of the Israeli security forces, and has no civilian jurisdiction within Israel. The IDF is headed by the Chief of General Staff, who is subordinate to the Israeli Defense Minister.
An order from David Ben-Gurion on 26 May 1948 officially set up the IDF as a conscript army formed from the ranks of the Haganah, Irgun and Lehi paramilitary organizations. The IDF has participated in all of the armed conflicts involving Israel since its independence. According to the think-tank organization GlobalSecurity.org, the number of wars and border conflicts in which the IDF has been involved in throughout its short history makes it one of the most battle-trained armed forces in the world. While it originally operated on three fronts—against Lebanon and Syria in the north, Jordan and Iraq in the east, and Egypt in the south—the IDF has shifted its focus primarily to southern Lebanon and the Palestinian Territories since the signings of the 1979 Egypt–Israel peace treaty and the 1994 Israel–Jordan peace treaty, with some incidents occurring across its border with Syria due to instability caused by the ongoing Syrian Civil War.
The IDF is unique amongst the militaries of the world due to its regulated conscription of women since its formation. It is one of the most prominent institutions in Israeli society due to its influence on the country's economy, culture and political scene. The IDF uses several technologies developed within Israel, with many of them made specifically to cater to the IDF's needs in its operational environment in the Levant, such as the Merkava main battle tank, the Achzarit armored personnel carrier, the Iron Dome air defense system, the Trophy active protection system for vehicles, and the Galil and Tavor assault rifles. The Uzi submachine gun is an Israeli invention and was used by the IDF until December 2003, ending a service that began in 1954. Since 1967, the IDF has had close military relations with the United States, including in development cooperation, such as on the F-15I jet, the THEL laser defense system, and the Arrow missile defense system.
The IDF is believed to have had an operational nuclear weapons capability since 1967, possibly possessing between 80 and 400 nuclear warheads, with delivery systems forming a nuclear triad of plane launched-missiles, Jericho III intercontinental ballistic missiles and submarine-launched cruise missiles.