Israeli strikes have pummeled the Gaza Strip for three days, killing at least 28 people, among them several children and five leaders of the Islamic Jihad militant group, according to Gaza’s health ministry. Israeli officials say their forces are targeting commanders of and weapons stored by the extremist group.

Islamic Jihad has fired more than 400 retaliatory rockets into Israel - with some reaching as far as central Tel Aviv - but most were intercepted by the country’s air defense system, according to the Israel Defense Forces. An Israeli man died Thursday in a rocket attack on the city of Rehovot.

It’s another grim cycle of violence - and the stakes are high as a new phase of the Israeli-Palestinian crisis unfolds, with Islamic Jihad emerging as an influential force across the Palestinian territories.

Here’s what to know about Palestinian Islamic Jihad and why Israel is targeting it in Gaza.

What is happening in Gaza?

Israel launched its latest round of strikes on targets in the Gaza Strip on Tuesday. Dozens of military aircraft have taken part, hitting apartment buildings, weapons factories and rocket launchers, according to the Israeli military.

In response, Islamic Jihad militants have sent more than 400 rockets into Israel. For the first time since the 2021 war, air sirens also went off in Tel Aviv, more than 40 miles from the Gaza Strip. Most rockets have been intercepted by Israel’s Iron Dome antimissile defense system, and the handful that weren’t intercepted have tended to land much closer to Gaza. Israel holds Hamas responsible for any violence originating from Gaza, though the two have not clashed directly in this round of violence.

Israel - which controls and restricts nearly all passage of people, goods and humanitarian services into and out of Gaza - on Tuesday announced a complete border closure for at least several days. The conflict-weary territory, about the size of Philadelphia, is home to some 2 million people, nearly half of whom are children. Unemployment and poverty are sky-high, and Gazans have limited to no access to clean water, stable electricity and medical care, or a way in and out of the narrow strip.

Why is this happening now?

Islamic Jihad is far smaller than Hamas, the extremist group that has ruled inside the Gaza Strip since 2007. But by firing rockets into Israel, Islamic Jihad is testing Hamas’s leadership and legitimacy. So far, Hamas has refrained from formally entering the air battle: Doing so might boost its standing in the short term, but could prove very damaging for Gazans still recovering from previous confrontations with Israel.

In the West Bank, Islamic Jihad has led attacks against Israeli soldiers and civilians and is increasingly popular among Palestinians disillusioned by the failure of politicians to achieve statehood, ensure safety and end the Israeli occupation. The Palestinian Authority, dominated by the Fatah party and led by aging and ailing President Mahmood Abbas, has only pockets of power and support as Israeli settlers and military rule continue to expand.

Pressure on Israeli Prime Minister Benjamin Netanyahu to use even greater force against Hamas, Islamic Jihad and Palestinians in general is also continuing to grow. Netanyahu needs to appease the extremist members of his government, with whom he allied to stay in power and fight corruption charges. Southern Israel, where most Islamic Jihad rockets land or are intercepted, is a stronghold of Netanyahu’s right-wing base.

Tensions crested after Khader Adnan, a 45-year-old father of nine and an influential member of Islamic Jihad, died in an Israeli prison on May 2 after an 87-day hunger strike. Adnan had undertaken hunger strikes and court battles to protest his charges and detention. Palestinian officials called his death “an assassination.” Shortly after, Islamic Jihad and Hamas launched about a dozen rockets into Israel, and Israeli war planes struck Gaza. The two sides agreed to a cease-fire brokered by Egypt, Qatar and the United Nations.

Last month, a regionwide war appeared on the brink of breaking out after Palestinian militants, including Islamic Jihad, fired rockets into Israel from Gaza, Syria and Lebanon. Israel struck Gaza and Lebanon in retaliation before a temporary cease-fire was reached.

What is Palestinian Islamic Jihad?

The group was established in the 1980s by Palestinian students in Gaza as an offshoot of the Muslim Brotherhood, a global Islamist movement founded in Egypt. Hamas was another offshoot. The United States has designated both as terrorist groups for their attacks on Israelis.

Islamic Jihad is committed to armed resistance against Israel, a self-described Jewish state established in 1948 on land Palestinians claim. Palestinians commemorate their displacement, known as the Nakba, later this month. The group is opposed to the 1993 Oslo accords, which never went into full effect, and any other political agreement with Israel. Though allied with the much larger and politically repressive Hamas, Islamic Jihad is considered more ideologically extreme.

Iran - mired in proxy conflicts with Israel - is the main foreign supporter of Islamic Jihad and provides funding, weapons, training, technologies and political cover, according to Israeli intelligence. Iran has also backed Hamas, though to a far lesser extent. Both groups remain focused on the Palestinian struggle.

Palestinian Islamic Jihad has boycotted the handful of Palestinian elections held since the creation of the Palestinian Authority in 1994. The Fatah-dominated PA, which has an increasingly limited rule in parts of the Israeli-occupied West Bank, is a rival of both Hamas and Islamic Jihad. Hamas’s political arm participated in the last legislative election, which it won in 2006. Some Palestinians voted for Hamas out of frustration with corruption among Western-backed Fatah leaders. But when Hamas entered the new government, the U.S.-led Middle East Quartet boycotted it.

Soon after, a Palestinian civil war broke out: Hamas took control of Gaza, where it instituted its own government, while the PA remained in the West Bank and led by Abbas. In response, Israel and Egypt imposed land and sea blockades.

When else have Israel and Islamic Jihad clashed?

Over the past year, Israel has launched near-daily, often deadly raids in Palestinian cities targeting, it says, fighters and militants behind attacks on Israelis. Last year, Israeli forces killed nearly 150 Palestinians in the West Bank and East Jerusalem, the highest number since the end of the last Palestinian uprising in 2005, according to the United Nations. In the first four months of 2023, Israeli forces have killed nearly 100 Palestinians, per U.N. figures. At least 18 Israelis and one foreign national have died in Palestinian attacks in Israel and the Palestinian territories this year.

Islamic Jihad members and affiliates have been behind many of these operations. They have also gained a following in refugee camps, such as in Jenin and Nablus, where fighters patrol to keep the military out. This new generation of armed groups has largely formed on a local level outside of Fatah and Hamas. Disillusioned by the perceived failures of their aging leaders, some Palestinians are attracted to Islamic Jihad because of its lack of adherence to established political ideology.

In August 2022, at least 47 Palestinians, including 16 children, were killed in the Gaza Strip in a three-day air battle that began after Israel assassinated an Islamic Jihad leader there. It was the deadliest exchange of fire since an 11-day war the year in 2021 - Gaza’s fourth war with Israel in 12 years, alongside countless skirmishes.

Israel and Palestinian Islamic Jihad also exchanged missiles and rockets for several days in 2019, after Israeli forces killed another of its top commanders in Gaza. Hamas notably sat out the 2019 and 2022 escalations.

In the deadliest war in 2014, more than 2,000 Gazans were killed, including about 500 children, and more than 70 Israelis, according to the United Nations.