Armed and trained by Iran and allowed to operate openly in Lebanon for years by Syria, Hezbollah has waged a guerrilla war against Israeli military forces in South Lebanon and carried out terrorist attacks against Israeli civilians for over two decades. 

Hezbollah (Arabic for "party of God") emerged in 1982 from the Shiite Muslim population of South Lebanon with the help of Iranian Revolutionary Guards who traveled to the Bekaa Valley in Lebanon to fight Israel following its incursion into the region.  Israel entered Lebanon in response to the Palestine Liberation Organization, which mounted repeated cross-border attacks against Israel after establishing its base in Lebanon in the early 1970s.

In addition to driving the Israeli military out of South Lebanon, Hezbollah was originally formed to establish an "Islamic Republic" encompassing Lebanon and Israel.  According to its 1985 platform, the conflict with Israel "is not only limited to the IDF presence in Lebanon" but to "the complete destruction of the State of Israel and the establishment of Islamic rule over Jerusalem." 

Hezbollah has also carried out attacks against Jews outside Lebanon, including the 1992 bombing of the Israeli Embassy in Buenos Aires, which killed 29 people, and the bombing of the AMIA Jewish community building two years later, also in Buenos Aires, that killed 85.  The group has also been connected to other attacks against Jewish targets in Africa, Sweden, Denmark, Thailand, the U.K. and Argentina.

Despite the Israeli army's withdrawal from its buffer zone in South Lebanon in 2000, Hezbollah reinforced its grip over that territory, acquiring missiles and armaments and entrenching itself on Israel's northern border.  In that time, Hezbollah has also increased its presence in the West Bank and Gaza, providing weapons, training and funds to Palestinian terrorist groups.