By Nicholas Blanford / Wadi Khaled

Syria long has been accused of stirring trouble in the territories of its neighbors by exporting unwanted people across porous borders - Kurdish separatists into Turkey, Sunni insurgents into Iraq and Palestinian militants and Al-Qaeda sympathizers into Lebanon. But with Syria reeling from the worst internal unrest since the ruling Baath Party took power nearly 50 years ago, it is Damascus' turn to complain about the alleged infiltration of foreign militants seeking to stir anti-regime violence. Amid President Bashar al-Assad's hard-soft campaign against the unrest (crushing violence against protesters on one hand; lifting the nearly half-century "emergency law" and promising reforms, on the other), the official media in Damascus is focusing on the threat from across its borders.

On Sunday, for example, a refrigerator truck filled with automatic weapons, grenade launchers, sniper rifles, night-vision goggles and ammunition was seized by Syrian customs on crossing into Syria from Iraq, according to Syria's SANA news agency. The driver, the report said, claimed to have been paid $20,000 by an Iraqi to deliver the weapons into Syria.

But the brunt of Syrian paranoia seems to be focused on Lebanon. Last week, Syrian state television aired the alleged confessions of three members of the Muslim Brotherhood who claimed to have been planning to incite protests and form armed groups on the instructions of Jamal Jarrah, a Lebanese parliamentarian belonging to the Future Movement, a Sunni political block headed by Saad Hariri, the caretaker prime minister and the bÊte noire of Damascus. Jarrah has denied the accusation, but the claim has ignited fresh tensions between the Syrian authorities and Lebanese opponents of the Syrian regime. "If any harm comes to Syria, then Lebanon will be harmed," said Ali Abdel Karim Ali, the Syrian ambassador to Lebanon, in what many Lebanese interpreted as a threat.

Hizballah and other Lebanese allies of Syria have seized upon the accusations to launch verbal attacks against their domestic political foes in the March 14 parliamentary coalition, which includes the Future Movement. March 14 retorted that the accusations suggested a "dangerous conspiracy against Lebanon" and warned the Lebanese "against getting involved in a new plan aimed at creating strife among them."

A look at Lebanon's northern border with Syria, from the standpoint of Wadi Khaled, a remote impoverished village of black basalt homes scattered over a hillside, makes it immediately clear just how easy it would be to slip from one side to the other. The border here follows the Kabir river. Kabir may mean "Great" in Arabic but this watercourse is barely larger than a small creek, flanked by dense thickets of trees and lush verdant pastures.

"Yes, it is very easy to cross, especially in summer when the river is low," says Mohammed, owner of an electrical goods store a stone's throw from the river. He says smugglers charge $1,000 per head to cross one way or the other. Most people crossing the border are either economic migrants (Africans, for example) who hope to find jobs in Lebanon, or Lebanese criminals on the lam who sneak into Syria until the heat has died down back home.

But are the Lebanese sending operatives in to subvert Damascus? The political traffic seems to be the other way around. Rami Nakhle, a Syrian opposition activist, slipped across the border in Wadi Khaled in January to avoid being arrested by the Syrian authorities for his anti-regime activities. A Syrian smuggler in Homs charged him $1,500 for the trip. Rami agreed, but said he would only pay once in Lebanon. The two men rode motorcycles from Homs until they reached the border, then continued on foot. But as they reached the river, they were ambushed by Syrian border guards. "They were firing in the air and we split up. They chased me but I kept running into Lebanon," Rami says. (See pictures of Protests in Lebanon)

Although he lost his guide, Rami bumped into another Syrian smuggler on the Lebanese side of the border who offered to take him to Beirut for only $500. Rami presently is in hiding in Beirut and, operates under the pseudonym Malath Aumran, using the internet to help organize protests.

Smuggling activities have slowed since the uprising in Syria began five weeks ago. Syrian troops have reinforced their border positions and increased the number of foot patrols along this stretch of the frontier. Wadi Khaled and most of the neighboring villages are populated by Sunnis and are supporters of the Future Movement which, as far as the Syrians are concerned, is good reason to keep a wary eye open for possible infiltrators. "Our blood belongs to Saad Hariri and we are with the Syrian uprising one hundred percent," says Ali, a young man sitting astride the ubiquitous Syrian-made motorcycles used for transport in the Wadi Khaled area.

Local residents say they are monitoring the border for possible Syrian infiltrators who they believe may attempt to create strife in Lebanon. Some members of Fatah al-Islam, an Al-Qaeda-inspired faction that fought a bloody three-month battle against Lebanese troops in a north Lebanon Palestinian refugee camp in 2007, entered Lebanon via the Wadi Khaled district. "We will let Sunni refugees come here, but we will not allow any Alawites to enter," says Ali, referring to the minority Alawite sect, an off-shoot of Shi'ite Islam whose adherents form the backbone of the Syrian regime.

Although the Kabir river provides a clear geographical marker for the path of the border, the Lebanese-Syrian frontier is less well defined elsewhere. Much of the border is in dispute, with claims and counter-claims that both countries are encroaching on each other's territory. The fault for the ill-defined nature of the border rests with the French mandatory authorities who never properly delineated and demarcated the frontier when the modern state of Lebanon was established in the 1920s.

Syrian border security concerns run highest in areas adjacent to Lebanese Sunni populations, but a few miles to the east, in the remote Shi'ite populated Hermel district of Lebanon's Bekaa Valley, a center of support for the Syria-allied Hizballah, the border restrictions are much more lax. It is through the rugged mountains of the eastern Bekaa that Hizballah is believed to bring much of its substantial arsenal of weapons from Syria. Locals allege that when the electricity supply is suddenly cut at night and cellphones lose reception, it means Hizballah's cross-border arms convoys are on the move.

At the tiny farming hamlet of Hawsh Sayyed Ali near Hermel, the border is marked by a concrete culvert and a narrow stream along which gushes icy snow melt from the mountains to the west. A Syrian border guard sitting in the entrance of a small concrete hut with the national flag painted on one wall stares curiously as a small group of people pass by a few yards away. A tractor carrying a trailer piled high with sacks of cement chugs down a steep ramp into the stream opposite the Syrian border post. The Syrian guard does not even glance up as the tractor driver follows the water course for about 50 yards before heading up another earth ramp onto the Syrian side.
"You have just watched someone smuggling cement into Syria," chuckles Hussein, a self-confessed smuggler and farmer.

On the other hand, the tractor's short trip may not have constituted an act of smuggling after all, because, according to standard maps of Lebanon, Sayyed Hawsh Ali lies almost one mile inside Syria. Just another bizarre anomaly along the porous and ambiguous Lebanon-Syria border.