Israel launched air strikes on southern Syria on Monday after dozens of people were killed in fighting between allies of the Syrian government and sects wary of the post-Assad order.
Syrian troops were sent to the Druze heartland of Sweida after 38 people were killed in clashes. The government said six of its troops were among the dead, while an estimated 30 government auxiliaries were also killed.
Druze sources said pro-Syrian government militias launched attacks on the city of Sweida from Sunni areas to its west as the province came under siege by government forces. A war monitor put the total death toll at 89.
The Syrian Defence Ministry said it had begun “spreading military units in the affected areas”. It blamed “an institutional vacuum” for “worsening the chaos”.
Israel later said its military struck a number of tanks in southern Syria. It did not provide details, but a source in Sweida said the area where the tanks were hit, between Sijen and Samii in Deraa province, had been a launchpad for attacks on the Druze.
The Israeli strikes were "a message and a clear warning to the Syrian regime - we will not allow harm to be done to the Druze in Syria," said Defence Minister Israel Katz. "Israel will not stand idly by."
Israel intervened in April to halt attacks on Druze communities in Damascus and Sweida that killed dozens of civilians. Syria contains most of the world's one million Druze, who follow an offshoot of Islam that is also present in Israel, Lebanon and Jordan.
The latest violence also follows the killing over two days in March of 1,300 Alawites in incursions by government forces and auxiliaries into Syria's coastal Alawite region.
Dozens killed in sectarian clashes in southern Syria
On Sunday, at least one Druze town was seized by militias from neighbouring Deraa, in the worst violence against the community of 800,000 people since the April clashes, sources said. Syrian authorities said they were “following the bloody developments in Sweida with worry and sadness”. They said troops had begun deploying in affected areas, providing safe passage for civilians and disengaging combatants.
Sweida and parts of eastern Syria, where the mostly Kurdish Syrian Democratic Forces are powerful, are the only areas where the Hayat Tahrir Al Sham (HTS) government that last year ended the rule of the dictator Bashar Al Assad does not exert control. The leadership of both the Kurds and the Druze have opposed what they describe as HTS's religious agenda under Syria's new President, Ahmad Al Shara.
The latest clashes started last week after Fadlalah Duwara, a vegetable seller and member of the Druze community, was abducted while driving his lorry on the main road from Sweida to Damascus, which is under government control. His tribe responded by abducting a man in a Sunni neighbourhood of Sweida.

The area is inhabited by members of Bedouin tribes who moved to the city decades ago from a rugged region on the outskirts. The attacks provoked a kidnapping cycle that broke into clashes in the city on Sunday, according to residents and sources in Jordan who are in contact with people in the province.
By Monday the situation in Sweida had calmed after most of the hostages from the two sides were freed. But the western outskirts came under attack by militias based in Lajat, Busra Al Harir and Busra Al Sham, the Druze sources said. They said the Druze town of Al Dour fell to the militias overnight, while Daara, another Druze town, has changed hands several times.
A Druze political figure close to the Druze spiritual leader Hikmat Al Hijri told The National that Sweida is “falling under siege”, with the 40th division of the new Syrian army backing the militias from Deraa who are attacking the Druze in the west. The 70th Division was deployed last month in the east of Sweida city, and since Sunday regular troops have provided manpower from the north. The south of Sweida province borders Jordan.
Suhail Thebian, a prominent Druze civil figure, said the attackers from the west were being met with heavy resistance. “If the incursion works out, there will be a sectarian massacre, like the one that befell the coast,” he said, adding that the authorities would blame “undisciplined elements” within their ranks.
“Al Shara wants to break the mountain in any shape of form,” Mr Thebian added. Sweida is known as the Mountain of the Arabs. It is where a failed revolt against French rule started in 1925. That uprising was crushed after two years but it helped carve out an image of the Druze as Syrians above all.

Sana, the official Syrian news agency, said Syrian security forces had been sent to the administrative borders between the Deraa and Sweida provinces. Secondary school exams due to take place on Monday were postponed.
Many Druze, particularly the minority's spiritual leadership under Sheikh Al Hijri, have resisted attempts by the central authorities to control the province by deploying new police units. Sheikh Al Hijri has accused the HTS government of extremism and lack of interest in a civil-based, democratic order to replace the past regime. HTS, a group formerly affiliated with Al Qaeda, led an offensive that ended five decades of Assad family rule in December.
In the last year of Mr Al Assad's rule, the Druze, led by Sheikh Al Hijri, mounted a peaceful anti-regime protest movement in Sweida, although the Assad regime maintained its forces in the area. The Druze have survived persecution by the French and the Ottomans, and retribution for a failed coup led by a Druze officer against the country’s Alawite rulers in the 1960s, as well as the 13 years of civil war that preceded the downfall of Mr Al Assad.
In the offensive that toppled Mr Al Assad, the HTS swept out from areas in northern Syria that it had run according to its strict interpretation of Islamic jurisprudence. Many inside the HTS rebel movement view the Druze – whose religion contains elements of Hinduism, Islam, Christianity and Judaism – as heretics.
But since becoming Syria's President in January, Mr Al Shara, the leader of HTS, has repeatedly signalled that no harm will come to members of the country’s many minorities unless they are found to have been complicit in the crimes of the former regime.