A wall of sandbags protects a restaurant in Haret Hreik, a majority mixed Shia Muslim and Maronite Christian neighbourhood in Beirut's Southern suburbs. (Sam Tarling/For The Washington Post)

At a small, family-operated firm selling building materials in Beirut’s southern suburbs, sales are picking up. But it’s not new construction that’s fueling business. It’s a run on sandbags for protection from car bombings.

Piled high on sidewalks outside banks and cafes in the Haret Hreik neighborhood, the sacks of grit serve as daily reminders of the price that residents of this Hezbollah stronghold are paying for the Shiite movement’s military support of President Bashar al-Assad in next-door Syria. One restaurant has gone a step further, erecting a thick concrete blast wall.

Lebanon has seen a spike in suicide bombings this year, with seven attacks since Jan.­ 1. Three occurred in the southern suburbs known as the Dahiyeh, now a major target of Sunni extremist groups. The al-Qaeda-linked groups Jabhat al-Nusra and Abdullah Azzam Brigades, as well as the much-feared Islamic State of Iraq and Syria, have asserted responsibility for the bulk of the bombings, calling for Hezbollah to pull its militants out of Syria.

Residents are bracing for more retaliatory attacks as Hezbollah enters another major battle in the Syrian civil war, backing Assad’s forces as they try to secure the border town of Yabroud.

For Ahmed Sharif Addin, owner of the building materials company, it means business, even if it’s a service he says he would rather not have to provide. He said he sells about 300 sandbags a day and as many as 1,000 a day right after a bombing.

“There’s a lot of demand,” he said. “People are scared.”

Committed to Assad

Much of Haret Hreik was reduced to rubble in air raids during the 2006 Israel-Hezbollah war but has since been rebuilt. Now the community is again under siege.

Businesses are suffering as residents avoid spending time in the streets. Parents say they use back roads to drive their children to school, away from main thoroughfares that could be targets. The suburbs’ outskirts, meanwhile, are plagued with traffic jams caused by vehicle searches at Lebanese army and Hezbollah checkpoints.

“It’s a constant feeling of fear,” said Ali Zaitar, 32, who works in a paint store next to a pockmarked dip in al-Arid Street, the scar of a Jan. 2 car bombing. Another explosion later that month occurred about 50 yards away. “This isn’t a life, it’s misery,” Zaitar said.

The Haret Hreik municipal ­government, which has spent $150,000 on security measures such as concrete blast barriers since the first bombing here in July, has encouraged businesses to hide sandbags behind advertising boards to lessen the “psychological impact” on residents.

“If the aim of these bombings is to terrorize this population, I ­believe they have succeeded in doing so,” said Imad Salamey, a politics professor at the Lebanese American University.

Although the attacks may be chipping away at Hezbollah’s support base, they are unlikely to have much impact on restraining its military activities over the border, analysts say. Hezbollah leader Hasan Nasrallah has vowed that his fighters will remain in Syria for as long as necessary.

In recent weeks, Hezbollah militants and Syrian army troops have encircled Yabroud, a town few miles across the border, as the Syrian air force has launched a fierce bombing campaign.

As operations in the area escalate, so do funerals in the southern suburbs. Three slain Hezbollah soldiers were buried last week, residents said.

Hezbollah says its operations in Syria are necessary to keep Lebanon secure, and its deputy secretary general, Naim Qassem, has said that Yabroud is the source of many of the explosives-packed vehicles that target Beirut. But the car bombings began in Beirut only last year, after Hezbollah announced its military support for Assad.

The violent backlash to that support has undercut Hezbollah’s political reputation as the “protector” of Lebanon’s Shiites, analysts say. Overstretched in Syria, its fighters have not responded to attacks from their traditional enemy, Israel.

Last month, after Israel bombed a Hezbollah position in Lebanon for the first time since 2006, the group said it would “choose the right time and place” to respond — a muted threat that suggested it did not plan to attack immediately.

On Wednesday, the Israeli army said it had shot two Hezbollah militants who were trying to plant a bomb on the border between Syria and the Israeli-occupied ­Golan Heights. Hezbollah has not responded.

‘We are with you’

In Haret Hreik, a neighborhood where emotional ties to Hezbollah run deep, leaving is seen as disloyal. Nonetheless, some families are relocating. Residents said that four or five have moved from al-Arid Street to elsewhere in Lebanon and that others would if they could afford it.

Hussein Mortada, 40, owner of a coffee shop, said he is trying to move to Canada, where his wife has relatives. With business down 80 percent this year, he has attempted to lure customers back by investing in $3,000 worth of sandbags, shatterproof window coating and potted plants on the street to prevent potential car bombers from parking there.

He hadn’t bothered with such measures at his cafe, a few miles away from the coffee shop at the epicenter of attacks. The cafe was hit when two suicide bombers struck Feb. 19.

“We try, but if someone is ­determined to kill himself, what can we do?” Mortada said.

The residents of Beirut’s southern suburbs are no strangers to the human toll of Hezbollah’s wars, and many remain resolute.

“Regardless, we are with them 100 percent,” said Abu Haider, a 43-year-old shop worker.

Above the sandbags on al-Arid Street, a banner showed a picture of a smiling Nasrallah and words that echoed Haider’s sentiment.

“Your smile revives the spirits,” it read. “We are with you, wherever you go.”