A young Palestinian takes part in a military-style exercise at a summer camp organized by the Islamic Jihad movement, in Khan Younis in the southern Gaza Strip, on Aug. 13. (Ibraheem Abu Mustafa/Reuters)

In an intense cross-border skirmish Thursday and Friday, Israeli artillery and aircraft struck more than a dozen military installations in southern Syria, as well as an alleged jihadist cell, in response to four rockets fired into northern Israel.

On Friday morning, Israel’s air force fired a missile into the ­Syrian-held side of the Golan Heights that killed as many as five people described by Israeli military officials as “a cell associated with Islamic Jihad.” According to the officials, the cell was behind the rocket fire into Israel on Thursday afternoon.

Islamic Jihad is based in the Gaza Strip and has members and cells in the West Bank and, according to the Israelis, in southern Syria. The Palestinian resistance movement fought a 50-day war with Israel in Gaza last summer alongside the Islamist militant movement Hamas.

Israel said it had “credible information” that the alleged Islamic Jihad rocket-launch crew, reportedly killed while driving in a vehicle 10 miles inside Syria, was directed by Saeed Izaadhi, who heads the Palestinian division of Iran’s Quds Force, a unit of the Revolutionary Guard Corps.

There was no immediate claim of responsibility for the rocket fire from Syria.

The Israelis offered no details proving that Islamic Jihad had fired the rockets — which caused little damage and no injuries in Israel — or that Iran was involved in ordering the attack.

But Israeli officials stressed in their remarks that the rocket fire toward Israel had been guided by Iran’s hand.

Prime Minister Benjamin Netanyahu said, “The states rushing to embrace Iran should know that an Iranian commander gave the cell orders to fire at Israel.”

Dore Gold, director general of the Israeli Foreign Ministry, said Iranian proxies were attacking Israel “before the ink was dry” on the nuclear deal reached last month between Iran and six world powers including the United States. Gold called the rocket fire “another clear and blatant demonstration of Iran’s continued and unabating support and involvement in terrorist attacks against Israel.”

Defense Minister Moshe Yaalon, meanwhile, accused Iran of seeking to “open a new terrorist front against Israel on the Golan Heights.”

The Britain-based Syrian Observatory for Human Rights, which closely monitors the fighting in Syria, confirmed that five men were killed Friday morning in the strike Israel said had targeted Islamic Jihad fighters.

According to the Observatory, at least two of the men were members of the National Defense Forces, described as civilian militias that fight in support of Syrian President Bashar al-Assad.

The Observatory also said that the artillery attacks and airstrikes Israel carried out against 14 military targets in southern Syria on Thursday night killed two Syrian government soldiers, including an officer.

Israeli security officials described the Syrian targets as “military infrastructure,” as opposed to tanks, artillery or troops.

Syrian state media issued a flurry of reports Friday on the cross-border flare-up.

The official Syrian Arab News Agency (SANA) reported that the five people killed in the vehicle were not fighters but civilians. The attack took place near a crowded market in the village of Kom, SANA said, near the Israeli-held part of the Golan Heights.

Citing an unnamed military official, the news agency said the Israeli attacks were designed to boost the “low morale” of “terrorist organizations” in the area. The Syrian government refers to its armed opposition as terrorists.

Iran has long been a key supplier of cash and weapons to Islamic Jihad, which has close ties with the Syrian government and has sent its fighters to train with Hezbollah militants in southern Lebanon. But in recent months, Palestinian media have reported a dramatic drop in Iranian financial support to the group, noting that Gaza-based members have been struggling with nonpayment of their salaries.

Zakaria al-Qaq, a professor of security studies at al-Quds University in Jerusalem, said relations between Islamic Jihad and Iran have been hurt, but not upended, over Iran’s support for Assad in the Syrian civil war and for the Houthi rebels in Yemen.

Islamic Jihad is more pragmatic than other anti-Israel Palestinian militant groups, such as Hamas, which moved its Damascus headquarters to Gaza in 2011 to protest the Syrian government’s killing of peaceful demonstrators during the initial phases of the country’s Arab Spring uprising.

“They are capable of being flexible,” Qaq said of Iran and Islamic Jihad. “They’ve had their differences, of course. But Iran and Islamic Jihad have common interests that they seek to maintain, and I don’t think you’ll see Islamic Jihad pull its presence out of Syria.”

Qaq added, “I don’t think the Iranians would completely stop the flow of money to Islamic Jihad.”

Naylor reported from Beirut. Carol Morello in Washington contributed to this report.

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