What is Hamas and why is it fighting with Israel in Gaza?

Hamas is a Palestinian armed group and political movement in the Gaza Strip. On October 7, 2023, the group attacked Israel, killing approximately 1,200 people and taking more than 250 hostages. This attack triggered a large-scale Israeli military operation in the Gaza Strip, resulting in the deaths of tens of thousands of Palestinians.

Hamas is designated as a terrorist organization by the United States, the United Kingdom, Israel, and many other countries, yet the group continues to launch rockets into Israel. In January 2025, Israel and Hamas reached an agreement to halt the war and release Israeli hostages and Palestinian prisoners.

Hamas was founded in 1987 as an offshoot of the Muslim Brotherhood, its name meaning "Islamic Resistance Movement." The group opposes the presence of Israel on what it considers Palestinian land and seeks to establish a state based on Islam, covering the occupied West Bank, East Jerusalem, and the Gaza Strip. However, Hamas has also indicated a willingness to accept a temporary Palestinian state only in the West Bank, East Jerusalem, and the Gaza Strip, without relinquishing its claim to all of historic Palestine.

Prior to the October 7, 2023, attack, it was estimated that Hamas had about 30,000 fighters, but Israel stated in August that its forces had killed more than 17,000 of them, though this number cannot be independently verified. Hamas has been the sole ruler of the Gaza Strip since winning the Palestinian elections in 2007 and forcibly expelling its rivals.

At the time of the Hamas attack on Israel on October 7, 2023, the group’s main leader was Ismail Haniyeh, who was in Qatar at the time, where Hamas has its headquarters. Haniyeh died in an explosion during a visit to Tehran, the capital of Iran, in July 2024, for which Israel later claimed responsibility. He was subsequently replaced by Yahya Sinwar, who had been Hamas’s leader in Gaza since 2017. Sinwar was killed by Israeli Defense Force soldiers in Gaza in October 2024; he was the planner of the October 7 attack and Israel's most wanted man.

Sinwar went missing at the start of the war and was thought to have spent most of his time hiding in tunnels under Gaza before he was killed. Several other senior Hamas commanders have also been killed by Israel since the war began. The conflict has resulted in the near-destruction of the group's infrastructure and public operating capacity in the Gaza Strip. Currently, Hamas's most prominent leaders include Sinwar’s deputy, Khalil al-Hayya, the group’s highest-ranking official outside of Gaza. Al-Hayya is currently in Qatar, leading Hamas's delegation in ceasefire negotiations with Israel.

Other key figures include Khaled Meshaal, head of Hamas's relations with Palestinian communities abroad, and Mahmoud Zahar, one of the group’s founders. Following Sinwar’s death in October 2024, Hamas will be led by a five-member committee until a new leader is chosen. The committee includes al-Hayya, Meshaal, Zahar, Jabarin, the head of the Shura Council, Muhammad Darwish, and a fifth, unidentified member.

Hamas’s most important ally is Iran, which is the group’s biggest supporter in terms of funding, weapons, and political support. Hamas led the deadliest attack in history against Israel, killing about 1,200 people, including more than 360 young people at a music festival. This unprecedented attack shocked the nation, with Hamas gunmen attacking border communities for hours and taking hostages.

Hamas says it is a resistance movement and calls the attack a response to what it says is decades of Israeli oppression, the killing of Palestinians, and the long-standing blockade of the Gaza Strip. Khalil al-Hayya, Hamas's highest-ranking leader outside of Gaza, defended the attack as Israel prepared to mark the one-year anniversary of the attack, saying it had put the plight of Palestinians on the world political agenda. “It was necessary to sound the alarm to the world, to tell them that here there are people who have a cause, who have demands that must be met,” he told the BBC's Jeremy Bowen.

Hamas also said the attack was a response to what it claimed were Israeli attempts to take over the al-Aqsa Mosque compound in Jerusalem, Islam’s third-holiest site. Hamas also wants the release of thousands of Palestinians held in Israeli jails. The year before the attack was also the deadliest year in the occupied West Bank since the UN began keeping records in 2005. By the end of the year, at least 505 Palestinians had been killed there, most of them by Israeli soldiers and settlers. Thirty Israelis were also killed in the West Bank in the same year.

All Palestinian factions and parties oppose the Israeli presence in the West Bank, as well as in occupied East Jerusalem and the Gaza Strip. They want the land to be part of a future independent state, which has the support of the vast majority of the international community. The UN’s highest court has deemed Israel’s occupation of the land and the settlements it has built there to be illegal. However, the current Israeli government does not recognize the right of Palestinians to have their own state, arguing that it would pose a security threat. It also claims that the West Bank is part of “Greater Israel.” Analysts believe the timing of the attack may also have been intended to undermine Saudi Arabia’s recognition of Israel, which at the time was seen as likely to happen.

Following the October 7 attack, Israel launched a large-scale military offensive against Hamas in Gaza. This began with airstrikes, followed by a ground invasion. Israeli Prime Minister Benjamin Netanyahu said that Israel’s goals included destroying Hamas, freeing the hostages, and ensuring Israel would not be threatened in the future. The Israeli government also said it wanted to allow tens of thousands of displaced Israelis to return to their homes in northern Israel, near the border with Lebanon, after attacks by Hamas ally Hezbollah.

According to the Hamas-run health ministry, more than 46,700 people have been killed in Gaza during the fighting, most of them civilians, and most of them women and children. The UN says that most of the 2.3 million population have been forced to leave their homes and that there is a “catastrophic” level of food insecurity. The Israeli military says that more than 400 Israeli soldiers have been killed in the fighting. Both Israel and Hamas have been accused of war crimes and human rights abuses.

The UN Human Rights Council said both sides had carried out attacks on civilians and were responsible for "murder or wilful killing." Both sides rejected the findings of the report. South Africa brought a case to the UN’s highest court, the International Court of Justice, accusing Israel of genocide. Israel said the case was “utterly baseless.” The ceasefire agreement reached in January 2025 aimed to halt the fighting and allow humanitarian aid to reach the people of Gaza. It was expected that the remaining 94 hostages would be released. Israel believes that 60 of the hostages are still alive and 34 have died. The agreement also anticipated the release of about 1,900 Palestinian prisoners, including some who have been imprisoned for years. In November 2023, the two sides reached a seven-day ceasefire, which saw the release of hostages and prisoners, and much-needed humanitarian aid was delivered to Gaza.

Since its inception, Hamas has carried out bombings, rocket attacks, and shootings in Israel, killing civilians and soldiers. Israel has conducted operations against Hamas in Gaza and its bases in East Jerusalem and the West Bank, killing its fighters. In these operations, Israel has killed many Palestinian civilians. There have also been several major conflicts between the two sides – in 2008-09, 2012, and 2014. The last major conflict between the two sides took place in May 2021, ending in a ceasefire after 11 days. Each round of fighting has resulted in casualties on both sides, the vast majority of whom have been Palestinians in Gaza.

The Gaza Strip is a territory 41km (25 miles) long and 10km wide, lying between Israel, Egypt, and the Mediterranean Sea. It was part of a proposed Arab state under the UN’s original partition plan of 1947. Gaza was then occupied by Egypt in the war that followed the creation of Israel, and then by Israel in the 1967 Six Day War. Israel withdrew its troops and about 7,000 settlers from the territory in 2005, although the UN still considers the land to be occupied. Gaza is one of the most densely populated places in the world. The UN says that just over three-quarters of its population are registered refugees or descendants of refugees. Even before the latest war between Israel and Hamas, the territory had one of the highest unemployment rates in the world, with most of its population living below the poverty line and dependent on food aid to survive. Israel controls Gaza's airspace, coastline, and shared borders. It also restricts the movement of people and goods.