According to Shin Bet, the Israeli Security Agency, Gaza militants fired more than 1,500 rockets at Israel during 2012 before Israel responded on November 14 by killing Hamas military chief Ahmed Jabari in a targeted air strike. Since then, Israeli Defense Forces say some 850 rockets have been fired from Gaza at Israel -- with more than 300 penetrating Israel's antimissile systems.

Israeli Prime Minister Benjamin Netanyahu has argued that "if Israel were to put down its arms, there would be no more Israel. If the Arabs were to put down their arms, there would be no more war."

* PALESTINIAN FACTIONS: HAMAS AND FATAH

Hamas is seen by its supporters as a legitimate resistance movement against the Israeli occupation of Palestinian territories in the West Bank and Gaza.

Created in 1987 after the start of the first intifada against the Israeli occupation, Hamas is -- according to its charter -- committed to the destruction of Israel. Hamas officials say they can neither recognize nor accept the existence of Israel until Israel recognizes their existence.

Hamas won the Palestinian parliamentary elections of 2006. But the victory sparked tensions with the rival Fatah faction -- the secular nationalist party of Palestinian President Mahmud Abbas that controls the West Bank. In fact, the two factions have been politically and geographically divided since the tensions escalated into violence in Gaza in June 2007.

The Politburo of Hamas, based almost entirely in nearby Arab countries, traditionally had been more militant than the movement's domestic political leadership in Gaza -- that is, until the Arab Spring changed the dynamics of politics in the Middle East. Since then, Hamas leaders in Gaza have increasingly argued that they are the movement's top leadership.

* SYRIA AND PRESIDENT BASHAR AL-ASSAD'S REGIME

Hussein Ibish, a senior fellow at the American Task Force on Palestine, points to the Syrian uprising as a key regional development affecting the foreign alliances of Hamas. The Hamas Politburo had close relations with Iran and Syria through its headquarters in Damascus. But writing recently in "Foreign Policy," Ibish noted that relations between Hamas and the Syrian government "completely collapsed" after Hamas registered opposition to the crackdown on dissent by President Bashar al-Assad's regime. As a result, the Hamas Politburo was forced to abandon its Damascus headquarters and its members scattered throughout the Arab world.

* IRAN AND PRESIDENT MAHMUD AHMADINEJAD

Iran -- a key ally of Assad's regime in Syria -- also has been a key supporter of Hamas for years. Iranian President Mahmud Ahmadinejad in 2010 called Hamas the true representative of the Palestinian people. That angered the rival Palestinian faction Fatah, which accused Iran of trying to divide the Palestinian people and foment strife. Meanwhile, Palestinian President Abbas said before the Arab Spring began that Hamas was being funded mainly by Iran. Ibish says the closure of the Hamas Politburo headquarters in Damascus has created "enormous strains with Iran, which is apparently supplying much less funding and material to Hamas than in the past." Nevertheless, Tehran continues to issue statements in support of Hamas. In September, Ahmadinejad said Israel was an "occupier" without roots in the Middle East and would be "eliminated." Previously, Ahmadinejad called Israel a "tumor" and said it should be wiped off the map.