Izz al-Din al-Qassam Brigades

The Izz al-Din al-Qassam Brigades are widely described as Hamas's military arm, through which Hamas plans and executes attacks against Israel and defends its control of the Gaza Strip.[5][6] The organization is also referred to by alternative names, including the Izz al-Din al-Qassam Squads, the Izz al-Din al-Qassam Battalions, and the Izz al-Din al-Qassam Forces.[1] Its name honors Izz al-Din al-Qassam, a Syrian-born preacher and guerrilla leader who organized armed resistance against British rule and Jewish settlement in Mandatory Palestine and was killed by British forces in 1935.[1]

A 2008 Israeli assessment characterized the Brigades as the center of Hamas's military system, responsible for planning and executing attacks against Israel and for defending the Gaza Strip from within.[6] A later study describes the organization as having developed into an organized military force integrated with Hamas's political and social structures.[7] Although Hamas has at times presented its political and military structures as separate entities, its founder Sheikh Ahmad Yassin articulated the underlying unity of the organization: "we cannot separate the wing from the body. If we do so, the body will not be able to fly. Hamas is one body."[8]

Hamas's formal military leadership is subordinate to its political leadership, which directs overall policy.[1][5] A CIA-derived profile states that the military wing reports to Hamas's Political Bureau leadership and is based in Gaza, while another profile says the Brigades claim cells across Gaza and the West Bank — known by its original, indigenous Jewish name of Judea and Samaria.[5][8] The Brigades' infrastructure has spanned both territories, with logistical support networks maintained abroad, and the distinction between Hamas's political and operative wings has often been difficult to draw in practice.[9]

Accounts of the Brigades' institutional origins vary. One account says Sheikh Ahmed Yassin created Hamas's military arm in Gaza in 1982 and that the apparatus took its final form as the Izz al-Din al-Qassam Squads, responsible for Hamas's most severe attacks from January 1, 1992.[1] The Combating Terrorism Center at West Point dates the Brigades' formal establishment to 1991, when Hamas appointed Salah Shehade of Beit Hanoun as its first commander.[7] Shehade had been a cellmate of Hamas founder Sheikh Ahmed Yassin, was released in a 1985 prisoner exchange, and was selected for the command role because of his education, charisma, and demonstrated ability to recruit and motivate fighters.[7]

In their earliest phase, the Brigades operated through small cells, reportedly consisting of four or five members under a single leader, targeting Israeli army posts and Jewish settlers.[7] This pattern changed on April 16, 1993, when Hamas carried out its first suicide bombing at the Mehola junction in Judea and Samaria; the attack killed the bomber and another Palestinian and wounded eight Israeli soldiers.[7] The adoption of suicide bombings marked a significant escalation in the organization's methods during the 1990s.[7]

The Congressional Research Service characterizes the Brigades' methods as having evolved from small-scale kidnappings and killings of Israeli military personnel to suicide bombings and rocket attacks directed at Israeli civilians.[10] It reports that attacks attributed to the Brigades since 1993 killed hundreds of Israelis and more than two dozen U.S. citizens, including dual U.S.-Israeli citizens.[10]

Published estimates of the Brigades' total strength vary considerably by period and methodology. A Jewish Virtual Library overview places the organization at approximately 30,000 fighters and an additional 7,000 reservists, while a CIA-derived estimate from 2019 gives 15,000–25,000 fighters.[1][5] An earlier estimate placed approximately 2,500 Brigades personnel apart from roughly 13,000–14,000 police, security, and intelligence personnel in the Hamas-led Gaza government.[8] A 2008 Israeli assessment estimated more than 10,000 Al-Qassam operatives in the Gaza Strip while stating that the routinely active core consisted of only several hundred skilled operatives, with the remainder expected to reinforce the Brigades during an emergency.[6] The same assessment placed the combined total of Al-Qassam and Hamas internal-security operatives at approximately 15,000.[6]

A 2008 report identified a northern brigade commanded by Ahmed Ghandour; apparently two Gaza City brigades under Ahmed Ja'abari; a central brigade under Ayman Nawfal; and two southern brigades, one in Khan Yunis under Muhammad Sinwar and one in Rafah under Ra'ed al-Atar.[6] Each territorial brigade was assessed to contain more than 1,000 operatives, divided into battalions, companies, platoons, and combat teams that included fighters, anti-tank personnel, saboteurs, and medics.[6] A 2014 assessment described six regional brigades or regiments, with estimated brigade strength of 2,500–3,500 personnel, while the Brigades themselves reportedly claimed 5,000 men per brigade.[11]

The Brigades' combined-arms composition has grown more sophisticated over time. A 2014 assessment identified infantry, rocket and mortar teams, air-defense personnel, anti-armor units, special forces trained for infiltration, engineers responsible for tunnel construction and maintenance, and dedicated intelligence personnel.[11] A 2008 assessment described the evolution from local terrorist networks into a hierarchical structure with semi-military patterns of action, including unified command mechanisms and support systems for manufacturing, acquiring, and smuggling weapons, while cautioning that the Brigades were not a classical military organization.[12]

Following Hamas's takeover of Gaza in June 2007, members of the Izz al-Din al-Qassam Brigades were recruited into official Palestinian security services. The cited analysis argues that this enabled the Hamas government to pay Brigades members from the government budget while maintaining forces oriented toward combat against Israel alongside policing and internal-security functions.[13]

The Brigades initiated the manufacture of rockets inside Gaza that became generically known as Qassam rockets. Three generations were listed by the Goldstone Fact-Finding Mission: the Qassam 1, developed in 2001 with a range of 4.5 kilometres and a 0.5-kilogram explosive load; the Qassam 2, developed in 2002 with an 8–9.5-kilometre range and a 5–9-kilogram explosive load; and the Qassam 3, developed in 2005 with a 10-kilometre range and a 20-kilogram explosive load.[14] The report noted that these rockets were generally unguided and incapable of being directed at specific targets.[14]

Beyond locally produced Qassams, the Brigades have operated an expanding arsenal. A 2008 assessment identified standard 122-millimeter Grad rockets, anti-tank weapons, improvised explosive devices, and an extensive underground network.[6] By 2021, the organization had reportedly developed or acquired rockets with ranges of approximately 70–100 miles, electronic-warfare capabilities intended to degrade Israel's Iron Dome missile-defense system, suicide drones, and explosive underwater drones.[1] Raw materials for missile production have included unexploded Israeli munitions reclaimed from battlefields, metal pipes left after Israel's 2005 withdrawal from Gaza, and cannon shells salvaged from British warships sunk during World War I.[15]

The tunnel network has been a defining feature of the Brigades' military posture. A 2008 assessment described tunnels used for smuggling weapons, personnel, money, and raw materials; enabling attacks and infiltration; providing concealment and escape routes; and connecting combat positions.[6] Tunnel construction expanded in subsequent years: Muhammad Deif was reportedly overseeing approximately 1,000 workers engaged in digging attack tunnels with heavy machinery in April 2015.[1] In April 2016, the Israeli military discovered a completed tunnel from Gaza into Israel reported to be approximately 110–130 feet underground and equipped with electricity, running water, and communications lines.[1]

The Brigades also pursued unconventional financing for their weapons programs. In early 2019, the organization solicited bitcoin donations through social media and websites including alqassam.net, alqassam.ps, and qassam.ps, claiming that bitcoin transactions were untraceable and providing instructions for anonymous donations.[16] U.S. authorities later seized 150 cryptocurrency accounts that had laundered funds to and from Brigades accounts and covertly operated one of the seized websites.[16]

The Brigades have employed a wide range of terrorist methods, including rocket launches, suicide bombings, shootings, improvised explosive-device attacks, attacks on military vehicles, kidnappings, and tunnel-based infiltration.[1] A 2007 review recorded 896 rocket hits and 740 mortar-shell hits in Israeli territory during that year, with the Brigades claiming responsibility for the majority.[12] During an unprecedented barrage in May 2007, launched amid Hamas's violent confrontation with Fatah, two Israeli civilians were killed by rocket fire.[12]

In June 2006, Hamas operatives infiltrated Israel, attacked an army post, and captured Israeli soldier Gilad Shalit.[1] A 2008 assessment described preparations for suicide bombings, complex attacks, and further tunnel infiltrations as continuing elements of the Brigades' operational planning.[12]

During Operation Protective Edge in the summer of 2014, Hamas fired 3,356 rockets toward Israel, while Israeli forces destroyed 32 Hamas tunnels and recorded 11 ceasefire violations involving rockets or mortars.[1] The Brigades claimed to have fired approximately 3,600 rockets during the conflict, including short-range Grad, Qassam, Katyusha, and mortar projectiles alongside longer-range Fajr 5, M75, J80, and R160 rockets.[17]

A 2008 assessment described the Brigades' defensive doctrine as asymmetric warfare against the Israel Defense Forces: small-unit and hit-and-run attacks, concealment within densely populated areas, extensive use of civilians as human shields, anti-tank weapons, improvised explosive devices, tunnels, and sustained rocket fire intended to pressure Israel's civilian population while Hamas forces continued operating inside Gaza.[6] Members of the Brigades were documented as active in front-line positions, engineering units, military police, weapons supply, tunnel preparation, ambushes, mortar operations, and rocket launches.[13] Brigades reports also described operatives meeting at the Ibrahim al-Maqadma mosque to coordinate fighting.[13]

Advanced training for Hamas military operatives has reportedly taken place in Iran, Syria, and Lebanon through Hezbollah.[6] The curriculum covered anti-tank warfare, sniping, intelligence tradecraft, artillery, weapons operation, rocket launching, explosives, and tactical methods.[6] Interview-based claims attributed to a senior Al-Qassam operative by the Sunday Times stated that hundreds of Hamas operatives had trained or were training in Iran and that approximately 600 had been trained in Syria; these figures derive from a single interview rather than independently verified totals.[6]

Iranian support has been acknowledged across multiple sources. The Brigades' weaponry, including longer-range rockets and anti-armor systems, has been linked to Iranian supply and financing. Yahya Sinwar summarized the relationship by saying, "Had it not been for Iran, the resistance in Palestine would not have possessed its current capabilities."[1] A Jerusalem Center for Public Affairs profile described Muhammad Deif as maintaining direct contact with Iran's Quds Force leadership.[18]

Hezbollah has served as both a training partner and a liaison organization. Saleh al-Arouri, a founding figure in Hamas's Judea and Samaria operations and a senior Hamas official, was identified as a coordinator of Hamas's military buildup and a liaison with Hezbollah and Iran before his death in a January 2024 airstrike in Beirut.[18][19]

The Brigades' first commander was Salah Shehade, appointed at the organization's formal founding in 1991.[7] Muhammad Deif became a senior Al-Qassam operative under the mentorship of Yahya Ayyash, the organization's chief bomb-maker.[18] An Intelligence and Terrorism Information Center profile states that, after Ayyash was killed in 1996, Deif became commander of Hamas's terrorist-operative wing.[9] He survived multiple Israeli targeted-killing attempts and suffered severe injuries in a strike on December 26, 2002, after which he operated underground.[9] A separate profile dates his formal command of the Brigades to July 2002 following Salah Shehadeh's death, while the U.S. Department of Justice identifies him as commander in chief from approximately 2002 until his death.[20][21]

Deif publicly announced the October 7, 2023 assault under the name "Al-Aqsa Flood."[22] Israel targeted him in southern Gaza on July 13, 2024, and the IDF confirmed his death on August 1 after an intelligence review.[2]

Marwan Issa served as deputy commander from approximately 2007 until his death in a March 2024 airstrike, according to the U.S. Department of Justice.[21][19] Saleh al-Arouri, a founding figure in Hamas's Judea and Samaria operations and a senior Hamas military coordinator, was killed in an airstrike in Beirut on January 2, 2024, along with Azzam Al-Aqra and Samir Fendi, who were also described as Al-Qassam commanders.[19] A Jerusalem Center for Public Affairs profile identified Bassem Issa as commander of the Gaza City Brigade's military wing from 2017 until his death in a 2021 Israeli airstrike and attributed an estimated 1,100–2,000 rocket launches against nearby Israeli communities to that period.[18]

The Brigades' long-serving public spokesman has used the name Abu Ubaida. He has been identified as Hudhayfa Samir 'Abdallah al-Kahlut and has served in that role since at least 2007.[23] In April 2024, the United States sanctioned him along with Hamas personnel connected to unmanned aerial vehicles and information operations, while the European Union placed the Al-Qassam Brigades under sanctions including asset freezes, travel restrictions, and a prohibition on providing funds.[23]

On October 7, 2023, Hamas launched a large-scale assault from Gaza that incorporated land, sea, and air components and has been described as the deadliest attack on Jews since the Holocaust.[21] A contemporaneous Jerusalem Post report placed the death toll above 1,200 and described the assault as involving a massacre and mass kidnapping.[24] Muhammad Deif, who had commanded the Brigades for more than two decades, publicly announced the attack under the name "Al-Aqsa Flood."[22]

The Congressional Research Service describes the assault as demonstrating an apparent evolution in the Brigades' capabilities, including drone munitions, personnel-capable gliders, and complex infantry operations involving thousands of personnel attacking across Israeli-controlled lines along multiple axes.[10] Palestinian Islamic Jihad claimed that its forces also participated, and other actors may have joined the assault, so not all attacking forces can be attributed specifically to the Brigades.[10]

Participation figures differ by scope and source. Hamas deputy leader Saleh al-Arouri stated that 1,200 Al-Qassam Brigades members entered Israel during the assault, while another overview estimated that approximately 6,000 Hamas terrorists participated in the broader invasion.[24][1] One reported reconstruction attributed to Israeli journalist Ayala Hasson described an order delivered to approximately 25 Hamas brigade and battalion commanders on September 23, 2023. It specified October 7 as the operation date and organized the attack in three waves: elite Nukhba forces, additional Nukhba forces with regular troops, and a subsequent civilian wave.[25]

The attack's multi-domain character — combining motorized ground assault, paragliders, naval infiltration units, and large rocket barrages — demonstrated that the Brigades had developed beyond the rocket-launching force of earlier years into an organization capable of complex operations.[10] In his opening statement, Deif claimed that more than 5,000 rockets had been launched in the first 20 minutes.[22]

The United States designated Hamas as a Foreign Terrorist Organization on October 8, 1997. The U.S. Treasury's Office of Foreign Assets Control lists the Izz al-Din al-Qassam Brigades and variant names as aliases associated with Hamas, with the entries also listed as Specially Designated Global Terrorists as of October 31, 2001.[3][26] The European Union designated Hamas as a terrorist organization in 2001; the United Kingdom proscribed Hamas in its entirety in 2021; and Australia made the same decision in February 2022.[1][3]

Egypt designated the Al-Qassam Brigades specifically as a terrorist organization in February 2015, accusing the group of financing, planning, and executing attacks that killed Egyptian citizens, including security personnel.[1] The Brigades and Hamas rejected the ruling.[1] An Israeli government report on the 2014 Gaza conflict identified Israel, the United States, Canada, the European Union, Australia, New Zealand, and Japan as jurisdictions that had designated Hamas or its military wing as a terrorist organization, while noting that the precise legal treatment differs across jurisdictions.[4]

The EU General Court removed Hamas from its terrorist blacklist in December 2014 on procedural grounds, but the European Court of Justice subsequently restored Hamas to the list.[1] In April 2024, the United States sanctioned additional Brigades-linked individuals, including spokesman Abu Ubaida and personnel connected to drone programs and information operations, while the EU imposed asset freezes, travel restrictions, and funding prohibitions on the Brigades.[23]

Hamas leaders have made contradictory claims about the degree to which the Brigades operate independently. One senior Hamas official described the Brigades as a separate armed wing whose leaders do not take orders from the political leadership, while Hamas founder Sheikh Ahmad Yassin maintained that Hamas is one body that cannot be divided.[8] A CIA-derived profile says the military wing reports to the Political Bureau, and a 2008 Israeli assessment states that Hamas's political leadership directed the movement's military wing.[5][6]

The 2008 assessment found that the distinction between the Brigades and Hamas's internal-security system was not sharply defined in practice and that internal-security personnel could reinforce the Brigades during an emergency.[6] A broader profile concluded that Hamas's operative infrastructure was guided by leadership both within the Gaza Strip and abroad, and that the political-operative divide was frequently difficult to locate in operational terms.[9]

The Combating Terrorism Center at West Point describes the Brigades as Hamas's armed pillar, responsible for planning guerrilla operations, procuring and smuggling weapons, recruiting and training fighters, operating tunnels and rockets, conducting kidnappings and cross-border raids, and supporting Hamas's political project by projecting military power and deterrence.[7] The same source describes Hamas's social-political network as providing recruits, resources, ideological commitment, and political legitimacy to the military wing, creating a relationship of mutual reinforcement.[7]

The Brigades are significant as the principal armed structure through which Hamas has developed and projected organized military power. Their evolution from small clandestine cells into a force using rockets, tunnels, drones, gliders, naval units, and coordinated infantry operations culminated in the complex assault of October 7, 2023.[7][10]

Within Hamas, the Brigades also connect armed operations to the movement's wider political and social network. That network supplies recruits, resources, ideological commitment, and legitimacy, while the military wing provides coercive power and deterrence, making a clean institutional separation difficult in practice.[7]

The Brigades' precise founding date differs across sources. Accounts variously refer to the creation of Hamas's military arm in 1982, the apparatus taking its final Al-Qassam form around 1991–1992, and its formal establishment under Salah Shehade in 1991.[1][7] Manpower estimates also vary substantially by date and definition, ranging from early estimates of a few thousand personnel to approximately 30,000 fighters and 7,000 reservists.[8][1]

Participation figures for the October 7, 2023 assault are similarly disputed in scope. Saleh al-Arouri claimed that 1,200 Brigades members entered Israel, while another overview estimated approximately 6,000 Hamas terrorists in the broader invasion; Palestinian Islamic Jihad also claimed that its forces participated.[24][10]

Jurisdictions differ in whether their legal measures name Hamas as a whole, the Brigades specifically, or the Brigades as an alias or component of Hamas.[26][4] Claims about Iranian, Syrian, and Hezbollah training and weapons assistance likewise derive from a mix of official assessments, interviews, and secondary reporting and therefore carry varying degrees of qualification.[6]