The selection of Yahya Sinwar, a Palestinian hard-liner, as the new leader of Hamas in Gaza is a further blow to Israeli-Palestinian relations and the international community’s hopes for peace in the Middle East. However, it doesn’t mean another war between Israel and Gaza is imminent. The 55-year-old Sinwar will replace Prime Minister Ismail Haniyeh, the leading candidate for leadership of the entire Islamist movement in Gaza, the West Bank and abroad. Haniyeh has served in the Hamas government in Gaza since 2007.Haniyeh is due to succeed Khaled Mashaal as the chairman of the Hamas politburo and will probably move to Qatar. Sinwar will not inherit the title of prime minister, but will be the de facto ruler in Gaza and supposedly the undisputed leader of both the political arm and the military wing of the Hamas movement, Izzadin Kassam. Sinwar is the first Hamas leader to be selected for this post from the military wing. In Israeli terms, he can be compared to a former general, with a strong background and leaning toward the military, who is appointed as a political leader.As a young guerrilla fighter, Sinwar was involved in the systematic murder of Palestinian collaborators and traitors who were accused of working for Israeli intelligence, police and other occupying authorities during the first intifada.In this capacity, bestowed upon him by Hamas founder and leader Sheik Ahmad Yassin, he showed a penchant for cruelty, determination and ruthlessness.For his murderous terrorist acts, he was sentenced by the Israeli military court to four life sentences in 1989.As with many other junior criminals and terrorists, the prison served as his school and prepared him for life.Inside the walls of the jail, he rose into prominence among Palestinian inmates in general and those affiliated with Hamas in particular. Within a decade, he became the undisputed leader of the thousands of Hamas inmates in Israeli jails. From his cell, he communicated with the commanders of the military wing and demanded the kidnapping of Israeli civilians and soldiers to be used as bargaining chips in prisoner swaps.In 2011, after 22 years in prison, he was released in the controversial Gilad Schalit deal. He quickly positioned himself to serve in an unofficial capacity as “defense minister,” a liaison between the military wing and the political echelon. In the welcome home demonstration following his release, 200,000 Gazans packed the streets to hear Sinwar deliver a fiery speech calling for an uncompromising military confrontation with Israel. He advocated an approach whereby Hamas would “take the battles into the enemy side” – in a sense, his speech was the antecedent to the strategy of constructing tunnels to infiltrate Israel.The appointment of Sinwar, together with a few other military commanders to the Hamas politburo, has put an end to the internal power struggle that has shaken the movement in the past year.He showed his ruthlessness once again when he ordered, in an unprecedented move, for Hamas to kill a senior commander whom he perceived as a rival and traitor, without first allowing him to stand trial.It is now apparent that the military wing is cementing itself as the dominant force of the movement, which has touted itself as an alternative to the PLO and the Palestinian Authority. And since the military wing is more interested in building an army and less interested in developing social welfare and political institutes, its “nation-building” will be less important.Sinwar and military commander Muhammad Deif will further push the movement to improve relations with Iran, in the hopes of receiving more money, training and weapons. This approach may affect the recent efforts by Mashaal to reconcile with Egypt.Surely Sinwar, who even in Hamas terms is considered an extremist in his perception of Israel, will be an even more bitter enemy. He opposes any compromise with Israel, even temporarily, and will demand a prisoner swap more forcefully.Nevertheless, he is not uncontrollable; the decision-making process in Hamas is long, elaborate and collective. It is not in the hands of one person. Sinwar will try to convince his colleagues to launch a war if, and only if, he thinks the military wing is ready for it. It is not yet around the corner.