BEIRUT: Hezbollah’s victory in the Syrian rebel stronghold of Yabroud is likely to increase security incidents and widen the sectarian divide in Lebanon, while boosting chances that the party’s popular base will be targeted by more terror attacks, analysts and experts said.

Yabroud’s fall has likely driven a “significant” number of rebels affiliated with radical groups such as the Nusra Front into Lebanon while failing to secure largely porous borders, they said.

“Yabroud represents Hezbollah’s second major strategic and symbolic victory against opposition forces in Syria,” said Charles Lister, a visiting fellow at the Brookings Doha Center who has studied the insurgency in Syria extensively.

“Their lead role in Qusair effectively secured them target status inside Lebanon, and this victory in Yabroud will undoubtedly consolidate that status.”

Syrian regime forces backed by fighters from Hezbollah Sunday entered the border town of Yabroud, a key battle in the fight to sever rebel supply lines from Lebanon. It is the second major victory in the area after forces loyal to embattled President Bashar Assad, also backed by Hezbollah, captured the key rebel-held town of Qusair.

The Syrian regime launched raids on the outskirts of the northeastern Lebanese town of Arsal hours after entering Yabroud. About seven dead bodies and 100 wounded entered Arsal Sunday. The Lebanese Army also captured 21 mostly Syrian gunmen attempting to cross into the country Monday.

Experts said it would be difficult to estimate the number of fighters fleeing into Lebanon from Yabroud, but a “significant” number are likely to belong to the Al-Qaeda-affiliated Nusra Front and the Islamic State of Iraq and Greater Syria (ISIS).

“Some of the fighters might have fled further up north into rural areas of Homs that remain out of regime hands,” said Aymenn al-Tamimi, a terrorism analyst who has written extensively on Syrian rebel groups. “Exact numbers are difficult to determine, but I think Lebanon is the most viable escape route.”

Al-Tamimi said that both Nusra and ISIS had fought in Yabroud, with Nusra playing a leading role in rebel efforts and rejecting offers of a cease-fire and surrender to the regime.

This increases the likelihood that rebel fighters fleeing to Lebanon are affiliated with the Nusra Front, as more moderate factions likely withdrew before the final assault to other villages on the border.

The Hezbollah-backed victory in Yabroud is crucial for the regime because it could bring about the severing of extensive supply lines for rebels all the way to Damascus.

“The fall of Yabroud effectively closes the back door to Damascus and eastern Ghouta, which has been the main source of rebel activity in the Damascus suburbs over the last year,” said Joshua Landis, the founder of the website Syria Comment and director of the Center for Middle East Studies at the University of Oklahoma.

“Lebanon has been a main source of rebel support and resupply since the beginning of the revolution.”

These supply lines are indicative of an existing infrastructure for rebel groups within Lebanon itself. That very same infrastructure that supplied the rebels could now be turned inward against targets in Lebanon.

“Rebels in the Qalamoun area and Yabroud were getting supplies from Lebanon,” said Aron Lund, the editor of the Carnegie Endowment’s Syria in Crisis site. “Some of the supplies have apparently been smuggled on to other fronts, like in Damascus, so there seems to have been fairly intense traffic.”

“That requires a bit of infrastructure on the Lebanese side, which will still be there if they lose hold of the Syrian network,” added Lund.

Al-Qaeda-linked militant groups already exist in Lebanon. The Nusra Front’s Lebanon branch and the Abdullah Azzam Brigades have both claimed responsibility for suicide bombings and rocket attacks against areas associated with Hezbollah, citing the party’s involvement in Syria.

Analysts said the fall of Yabroud itself would not lead to a decline in suicide bomb attacks in Lebanon.

Security sources have said in the past that many vehicles used in bombings in Lebanon in recent weeks and months were rigged in Syria, specifically Yabroud, before being smuggled into Lebanon.

But the car bombs are not particularly challenging to prepare and militants here can draw on an preexisting infrastructure in Lebanon that was previously used to supply rebel groups.

“While Yabroud was clearly a valuable launch site for Grad rocket attacks into the Bekaa and allegedly as a transit point for car bombs headed into Lebanon, this could be replaced,” Lister said.

“Attacks against Hezbollah and Iranian targets in Beirut and in eastern Lebanon will continue, and likely accelerate in frequency,” he said. “While the scale of such attacks may drop off in the near term, additional resources and cross-border routes will see this recover with time.”

Even if a regime victory over the remaining border towns creates a hostile zone for rebels, it is unlikely that the porous borders could be closed off entirely to smuggling operations and cross-border raids. ISIS already operates that way on the Iraqi-Syrian border, and other routes and launching pads for attacks can be identified.

“I am less inclined to see a lull in attacks with the regime capture of Yabroud,” Tamimi said. “The border areas in general are porous, and the regime, even with Hezbollah support, lacks the manpower to shut off comprehensively the border areas to rebel movements.”

In addition, the victory in Yabroud is likely to fuel sectarian tensions in Lebanon, increasing the Sunni community’s sense of injustice.

Imad Salamey, associate professor of political science and international affairs at Lebanese American University, said the regime’s victory in Yabroud would fuel a sense of “despair” in Lebanon’s Sunni community, which increasingly views Syria’s war through a sectarian lens.

“Definitely Sunni-Shiite tension is on the rise, and the sense of injustice, and of being overwhelmed by the Syrian Army and Hezbollah, will create a lot of extremism and will lead to significant instability in the region.”