The brown sedan kicked up dirt as it sped along the small trail straddling Lebanon's border with Syria — another reminder how hard it will be for Lebanon to keep weapons and rockets from being smuggled in from Syria to rearm Hezbollah.

"There goes another one," growled farmer Ibrahim al-Halabi, taking a break from pruning trees in his fruit orchard to point to the car trailing a cloud of dust across the barren hills on the horizon.

"He is bringing cheap petrol from Syria," guessed al-Halabi, a 62-year-old father of five from the Lebanese border village of Yanta.

Smuggling across the porous Lebanon-Syria border has for decades been good business for hundreds of Lebanese and Syrians, who benefited from lax controls and even outright collusion by authorities to run their rackets with near impunity.

But now the issue has become more serious.

Policing the border to stop the illegal flow of arms to Hezbollah through Syria is the next priority for the Lebanese government and its Western backers as they press ahead with the implementation of a U.N. resolution that ended the 34-day war between Hezbollah and Israel.

Syria has balked at the suggestion that U.N. peacekeepers could be deployed along its border with Lebanon, and Hezbollah has warned such a move would result in "negative consequences."

But Israel, which repeatedly struck the border area during the war, says it must be done and has threatened to attack suspected convoys coming into Lebanon from Syria.

Hezbollah, which is backed by Syria and Iran, had for years received its arms shipments through official border crossings with Syria. That continued, albeit with some difficulty, after international pressure forced Syria to end its 29-year occupation of Lebanon last year.

But Hezbollah may now have to use smuggling routes as it seeks to replenish its arsenal — putting much of the focus on the rugged, porous border.

"Some of the more delicate and small hardware could be smuggled through the airport," said Lebanese analyst Helmi Moussa of the leftist As-Safir daily. "But there is no substitute for the overland arms shipments from Syria."

Already, the Lebanese army has beefed up its presence on the border, with up to 4,000 soldiers now deployed in the area, according to Lebanese security officials. Some of the major illegal routes — there are about 60 in total in addition to four official ones — have been blocked by dirt and rocks, according to the officials, who spoke on condition of anonymity because they are not authorized to speak to the media.

Trenches, some as much as five yards deep, were recently dug on some of the bigger smuggling routes to prevent their use, the officials said. The army has also stepped patrols along the border.

The five-mile stretch of secondary road leading to Yanta, for example, now has three army checkpoints. The road leading to the border past al-Halabi's orchard on the edge of Yanta, a Druse village of some 3,000 people, was blocked by a mound of earth and rocks.

But complete control of what comes across from Syria would be a tall order.

Some illegal dirt tracks are wide and firm enough to support large trucks. The smaller ones are used by mules which often are so familiar with the routes that they make the journey across unaccompanied by humans, according to residents.

"Here, you have small trucks and mules doing the cross-border run," said Mohammed Yassin, a Lebanese who runs a trucking business in the border village of Majdil Anjar. "The huge trucks are used across the northern border," he knowingly pointed out.

On the road between Masnaa, the main official crossing between the two countries, and Majdal Anjar tire marks can be seen on the steep hills astride the border several hundred yards to the east.

Hezbollah leaders so far have dismissed the idea that the closer scrutiny of the border will hurt their arsenal. Hezbollah leader Hassan Nasrallah had boasted before the war that his group had "more than 12,000 rockets." After the war, he said less than 50 percent had been used and that his earlier figure could have meant many more than 12,000.

Israel says it destroyed 50 percent of Hezbollah's rocket capabilities.

Nasrallah's second-in-command, however, said in a recent interview that Hezbollah's present arsenal could be as much as 90 percent of what it was before the war. The group is in no hurry to replace the rockets it used in the war, he said.

"I don't think the question of arms is a problem for us," Naim Qassim told the pan-Arab daily Asharq al-Awsat. "They are tiring themselves with deployments on the border ... their methods will not deter the resistance."

Such statements could, however, be just an attempt to downplay a serious threat.

Many believe the monthlong fight against Israel must have chipped off a large chunk of Hezbollah's arsenal — primarily assault rifles, rifle propelled grenades, anti-tank missiles and mortars. They note the group is almost entirely dependent on material assistance from Syria and Iran.

The land border is not the only issue, of course: Smuggling also has occurred by sea and air. Under the cease-fire agreement, Lebanon's Mediterranean coastline and only international airport will be monitored by European peacekeepers.