Yahya Sinwar was born in 1956 and grew up in the Southern Gaza refugee camp of Kahn Yunis, where he became part of a core group of highly devoted Muslim Brotherhood activists who created Hamas as a Brotherhood affiliate in 1987. In the 1980s as well, Sinwar helped establish the prototype for Al Majd (The Glory), the Hamas military and intelligence wing which later became known as the Izz al-Din al-Qassam Brigades. According to The Clarion Project, Sinwar during that time period developed a reputation for being “ruthless and extremist even by Hamas standards,” and “was particularly keen on punishing 'morality' offenders and killing Palestinians he suspected of collaborating with Israel.” Indeed, he reportedly killed a number of them with his bare hands.
In Khan Yunis, Sinwar formed a lasting friendship with Mohammed Deif, who not only serves today as chief commander of the aforementioned al-Qassam Brigades, but also has been Israel’s “most wanted” terrorist since the late 1990s due to his involvement in such crimes as kidnapping Israeli soldiers, dispatching suicide bombers, and planting explosives on buses.
In 1988 Israeli authorities arrested Sinwar and sentenced him to four life terms in prison for his terrorist activities against Israel and his role in murdering suspected Palestinian collaborators. At one point during his incarceration, Sinwar was successfully treated for a brain tumor in an Israeli hospital.
In 2011 Sinwar was set free as part of a deal in which Israel exchanged 1,027 Palestinian prisoners in return for Israeli soldier Gilad Shalit, whom Hamas had been holding captive for more than five years.
During the 2014 military conflict known as Operation Protective Edge, where Israel sought to degrade and destroy Hamas's military and terrorist infrastructure in Gaza, Sinwar served as one of the terror group's senior military leaders. When a cease-fire was eventually being negotiated, he pressed Hamas to exact additional concessions from Israel as prerequisites for a pause in the fighting.
In 2015 the U.S. government placed Sinwar on its terrorism blacklist.
According to a New York Times report: “Mr. Sinwar is believed to have been behind the detention, torture and killing of a Hamas commander, Mahmoud Ishtiwi, who was initially held for embezzlement in 2015. Months later he [Ishtiwi] was killed, accused of committing 'moral crimes' — amid suspicions of gay sex — that Mr. Sinwar apparently feared could lead to extortion and compromise Hamas.”
In a secret election which was held in February 2017, Sinwar was named to replace Ismail Haniyeh as the head of Hamas's Gaza operations. The Clarion Project reports that Sinwar, in his acceptance speech following his electoral triumph, “spoke of resorting to all measures to free Hamas prisoners from Israeli jails, recognized as code words for the green light to kidnap Israeli civilian and soldiers to use as bargaining chips.” Sinwar's victory, said Tel Avib University political science professor Shaul Mishal, “indicates that Hamas’s military wing, which is more hardline and extreme than the political leadership, has taken charge of an important position in Hamas’s leadership.”
According to a February 2017 report in The Guardian: “Sinwar’s outlook … is far more narrowly focused on Gaza than [Khaled] Meshal’s or other members of the old guard in Hamas’s political leadership, who are concerned with the long-running national unity talks with Mahmoud Abbas’s Fatah in the West Bank. Since his release by Israel in 2011, Sinwar has built up his power in the secretive military wing and is believed to have ordered the execution of a top rival last year in a power struggle.”
Over the years, Sinwar has cultivated a reputation as a fanatical, uncompromising zealot for the cause of Islamic supremacy and the annihilation of the Jews. For example, the Israeli newspaper Haartez reports that “Palestinians who have met with Sinwar characterize him … as someone who speaks in apocalyptic terms about perpetual war with Israel.” Similarly, the website IsraelStreet.org portrays Sinwar as someone known for his “unpredictable bursts of violence that have caused all of those in Gaza, including Hamas members, to fear him.” And Yaron Blum, a former senior official in the Israeli domestic intelligence agency known as Shin Bet, describes Sinwar as follows: “He is charismatic, he is not corrupt, he is modest and he advocates action.... He will do all he can to carry out terror attacks.”
Kobi Michael, an analyst and former head of the Palestinian Desk at Israel’s Ministry for Strategic Affairs, notes that Sinwar is a “bitter enemy” of the Egyptians who advocates cooperation with the Islamic State (ISIS) in the Sinai, and who is allied with Iran.