ARSAL, Lebanon (AP) — This Lebanese border town has become a safe haven for war-weary Syrian rebels, a way station for wounded fighters and home to hundreds of frightened Syrian refugee families.

Residents of Arsal, a Sunni Muslim town of 40,000, say they have strong motives to help those trying to topple Syria’s regime: they themselves were harassed and abused by it during three decades of de facto Syrian control of Lebanon.

But in siding with the rebels, many of them fellow Sunnis, Arsal is also deepening rifts with its Shiite Muslim neighbors in the Bekaa Valley that runs along Lebanon’s eastern border with Syria. Large areas of the scenic valley are controlled by Hezbollah, the powerful Shiite militia that is supporting and — according to the U.S. and the Syrian opposition — also fighting alongside Syrian President Bashar Assad’s forces.

For now, Lebanon’s rival political and religious groups have largely tried to keep a lid on domestic tensions stoked by the conflict next door, with collective memories here still scarred by Lebanon’s own 15-year civil war that ended in 1990. But any major escalation in Syria or miscalculation by the combatants’ Lebanese supporters could ignite Lebanon’s explosive sectarian mix.

Unlike some parts of Lebanon, the Bekaa has not been hit so far by sectarian violence linked to the bloodshed in Syria, although a drive along the valley’s bustling main thoroughfare and the string of towns that line it, shows where the region’s Shiite and Sunni loyalties lie.

In predominantly Shiite Baalbek, one of the Bekaa’s larger towns, a downtown billboard shows Hezbollah leader Hassan Nasrallah next to Assad, who is decked out in a military uniform and aviator glasses. “They will not weaken our resolve,” reads a defiant caption.

The presence of Iran, the region’s Shiite power and a patron of both Hezbollah and Assad, is also visible: A poster of Iranian President Mahmoud Ahmadinejad, with the slogan, “We can,” hangs from roadside poles along a four-lane highway that signs boast was partially funded by Tehran.

A turn off the highway and down a winding uphill road, leads east toward the Syrian border and Arsal.

Homes here are bare-bones, made of raw gray cinderblock, without stone facades. A spray-painted Syrian rebel flag — with green, white and black horizontal stripes and three red stars on the white — decorates one of the walls in the center of town.

Bassel Hojeiri, principal of the local middle school, said people in Arsal back the rebels as fellow Sunnis fighting a regime controlled by Alawites, an offshoot of Shiite Islam, but also because of deep-seated hatred of Syria’s rulers.

As a border town, Arsal suffered under a particularly oppressive Syrian military presence when Damascus held sway in Lebanon from 1976 to 2005. Syrian troops at checkpoints near Arsal would sometimes beat area residents, arrest them without reason, demand cash or even seize cars, said Hojeiri, 37, a former mayor of Arsal.

“People hated them,” Hojeiri said of the Syrian occupiers. “Now hopefully their time is ending.”

The town has stood by the rebels from the start, and now is deeply involved in the conflict. Last month, Syrian warplanes in pursuit of rebels fired missiles that struck near Arsal. Lebanese media have also suggested weapons smuggled from Lebanon to the rebels go through Arsal; residents acknowledge there’s a rich tradition of smuggling in Arsal, but say they don’t know anything about arms smuggling.

Volunteers from Islamic charities have sneaked scores of wounded rebels into Lebanon, driving them from there to hospitals in Tripoli, a Sunni stronghold in northern Lebanon, and bypassing clinics in Hezbollah-run areas in the valley, said Mohammed Hojeiri, a local activist.

Arsal has also taken in hundreds of Syrian refugee families, most from villages in Homs province, about 25 kilometers (15 miles) to the northeast. Some of the refugees rent apartments, while others live with Arsal families or in a small camp on the outskirts of town, where tents are being replaced by cinderblock shacks to prepare for the harsh mountain winter.

Rebel fighters have also used Arsal as a temporary haven to rest from the fighting across the border.

Peach farmer-turned-fighter Mohammed Yousef left his village of Zara in Homs province late last month after airstrikes destroyed his home and many others in the village. He reached Arsal after a seven-hour cross-border trek across mountainous terrain, he said, adding that several dozen of his fellow rebels do the same from time to time.

“Arsal is the … mother of the revolution,” the 25-year-old said affectionately of his Lebanese hosts who have sheltered his extended family of 10 in an empty building.

Yousef dismissed Syrian troops as largely ineffective, saying most can be bribed, but swore to exact revenge from Hezbollah, which he blamed for the destruction in his village. “We want to slaughter Hassan Nasrallah, the dog,” Yousef said of the Hezbollah leader. “He shelled us, he destroyed our houses, and killed our children.”

Hezbollah denies that it is fighting alongside regime forces, and a spokesman declined further comment Monday.

Lebanese security officials have said a number of Hezbollah activists recently buried in the Bekaa Valley had been killed in fighting in Syria, while Susan Rice, the U.S. ambassador to the United Nations, told the U.N. Security Council on Monday that “Nasrallah’s fighters are now part of Assad’s killing machine.”

Hojeiri, the school principal, said tensions between Shiites and Sunnis in the valley have been rising since the start of the Syrian revolt. Each side is aware of the other’s loyalties, and people are careful not to talk about politics when someone from the other sect is present, he said.

“People here don’t want another (sectarian) war,” he said.

In the past, ties between the communities were civil and even warm, he said, noting that some 200 men in Arsal are married to Shiite women from nearby villages.

For years, religious differences seemed unimportant, he said. Even during Lebanon’s civil war, with its frequently shifting alliances, Shiites and Sunnis were partners more often than they were foes.

Timor Goksel, a former official in the U.N. peacekeeping force in south Lebanon, said he believes the two sides have too much to lose by bringing the Syrian conflict home.

“Sunnis are very much involved in stone quarrying and the Shiite families are mostly involved in the hashish business,” he said. “Both sides respect each other’s turfs and have their own livelihoods, hashish and stone.”

Perhaps that’s why the valley has not seen sectarian clashes — unlike the majority-Sunni Tripoli, where sporadic fighting between pro- and anti-Syrian groups has killed more than two dozen people since May.

However, Sarkis Naoum, a columnist for Lebanon’s An Nahar daily said the sectarian tensions bubbling under the surface could erupt at any time.

“If anything major happens, what is happening in Syria could expand into Lebanon,” he said.