Hamas, the rulers of the Gaza Strip, is overrun by extremists supported by Iran.
Several Gazan factions supported by Muslim countries compete in the military escalation against Israel.

Hamas

An offshoot off the Muslim Brotherhood, the group had ruled the Gaza Strip since forcefully seizing control from the Palestinian Authority (PA) in 2007. In recent months, it has seen Iran cut its financial aid (formerly amounting to $500 million per year) as a result of criticism of Hamas leaders’ exile in Damascus, where they have opposed Syrian leader Bashar al Assad’s repression of opposition groups.
To stay financially viable, they have sadly had to seek our Egyptian, and in particular, Qatari sponsors. But since the last Israeli incursion into Gaza in January 2009, its military branch has completely overhauled its stocks. Thanks to Iran, the development and reach of Hamas’ missiles has considerably extended to as far as Tel Aviv. Aside from Katioucha rockets, the Hamas arsenal comprises Grad and Fajr missiles, as well as an Iranian-Chinese type of Katioucha ( with even greater reach). To prepare themselves for a subterranean war, like that which Hezbollah fought against the Israeli army in 2006 in Lebanon, their untied forces were equipped with a sophisticated communications system and their missiles to a steering system provided by Iran. Hamas also has troops trained in improvised explosive devices (IEDs), which can cause serious damage to military convoys. Before its break from Iran over Syria, Hamas sent tens of trainees each year to be instructed by activists in Syria and Iran. Their fighters also took instruction in Sudan, all of which countries have been repeatedly targeted by the Israel Defence Forces (IDF) in recent years.
At the end of 2011, Nigerian intelligence services intercepted 13 Iranian arms containers en route to Hamas, camouflaged in construction materials. The missiles’ spare parts were then to be forwarded on to Gaza through smuggling routes in the Egyptian Sinai Peninsula.

Islamic Jihad
The group claimed responsibility for the firing of the Iranian-made Fajr 5 missiles than reached Tel Aviv for the first time Thursday. Jihad is the closest Palestinian faction to the Iranian regime, but its nuisance capabilities are far weaker than those of Hamas. It has neither fallen out with Iran or Syria. Severely impaired by international sanctions, Tehran nevertheless has withheld its financial support of the group since 2009. It has not claimed responsibility for any attacks against Israel since 2008, instead concentrating its efforts of firing rockets at the Jewish State. Hamas has turned against the group in recent months, leading to a distinct deterioration in their relations. Backed by Iran and Syria, Jihad looks to take advantage of the current crisis to strengthen its stance ahead of Hamas, as the leaders in the war against “the Israeli enemy”.

The Jihadist movement
The group prospered following the fratricidal in-fighting which dominated Hamas and the PA, following the 2007 Gaza coup. A handful of sub-groups (The Army of Islam, Journeymen of Allah) comprise several hundred members. They recruit from disillusioned former Hamas members in light of their move into administration in Gaza, with a smaller proportion of foreigners penetrating the group via the tunnels in Sinai.
These groups claimed to be al Qaeda, but none of them were indoctrinated by its leader Ayman al-Zawahiri. They would have acquired rockets following raids on former Libyan leader Muamar Gaddafi’s stocks last year, after his regime’s fall. They hold Hamas responsible for slowing down their assault on Israel. Iran is accused of having taken advantage of the Egyptian army’s slackness in patrolling the Sinai Peninsula, which it is said has enabled Jihadist groups to penetrate certain refugee camps in the Gaza Strip.