It's hard to believe much of anything happens along most of Iraq's border with Syria. For hundreds of miles a modest sand berm that marks the dividing line between the two countries snakes through flat desert, with occasional villages or Iraqi Border Police forts providing the only human contact.  When I traveled to the border in August to cover U.S. Army troops advising border police units, it seemed these soldiers had a thankless task.  They lived at a small outpost with few creature comforts, executing a mission that often involved day-long humvee drives along the border that could be tedious, exhausting, and sometimes downright boring.  The nearest city, Mosul, was a roughly 40-minute helicopter ride to the west.  The Army combat outpost's close proximity to the border was underscored by the fact that helicopters had to immediately bank left upon takeoff; otherwise, in mere seconds, they would have crossed into Syrian airspace.

Yesterday came news of a cross-border raid by U.S. special forces into Syria aimed at striking a staging point for insurgents traveling into Iraq via the Anbar province.  The Associated Press took a look at the current state foreign fighters moving into Iraq:

The flow of foreign fighters into Iraq has been cut to an estimated 20 a month, a senior U.S. military intelligence official told the Associated Press in July. That's a 50 percent decline from six months ago, and just a fifth of the estimated 100 foreign fighters who were infiltrating Iraq a year ago, according to the official, speaking on condition of anonymity in order to discuss intelligence reports.

Ninety percent of the foreign fighters enter through Syria, according to U.S. intelligence. Foreigners are some of the most deadly fighters in Iraq, trained in bomb-making and with small-arms expertise and more likely to be willing suicide bombers than Iraqis.

Foreign fighters toting cash have been al-Qaida in Iraq's chief source of income. They contributed more than 70 percent of operating budgets in one sector in Iraq, according to documents captured in September 2007 on the Syrian border. Most of the fighters were conveyed through professional smuggling networks, according to the report.

In recent weeks, military commanders have increased their focus on the threat from militants in Syria who are blamed for cross-border attacks in western Iraq and for fueling violence in Mosul.

"The Iraqi security forces and the Iraqi intelligence forces feel that Al Qaeda operatives and others operate [and] live pretty openly on the Syrian side," Marine Maj. Gen. John Kelly, commander of U.S. troops in western Iraq, said at a briefing for reporters last week. "And periodically we know that they try to come across."

Among IBP forces all along the border, the single common denominator is almost always the same: fuel is scarce. Out here, having enough fuel means being able to fill a vehicle to a quarter tank. Without fuel the IBP’s machine gun-mounted Chevy pickup trucks cannot patrol the border, or deliver supplies. Generators which could provide electricity for recharging radio batteries and spotlights sit idle. Major James Moses, head of a transition team responsible for the southern portion of Ninawa’s border, recounted with amusement seeing one border policeman mix small amounts of gas and kerosene to make diesel fuel.

“I don’t know how he knew what to do, and what amounts to mix, but he did it” Moses said. “These guys know how to make something out of nothing.”

Moses also pointed out that even if the border police were able to strengthen their numbers to fill in the unguarded gaps along the border, there wouldn’t be enough fuel to sustain the larger force.

Iraqi Colonel Abed Al Karem, head of a local IBP battalion, expressed hopelessness over his unit’s fuel shortages. The problem, he said, exists at the IBP’s higher levels, and is beyond his own control.

“Sometimes I just sit down and I think: why [do we have this problem], it’s only fuel,” he said. “Iraq is all fuel. It is the first nation of fuel. Here in Iraq the fuel is more than water.”

Fuel and power shortages affect not only the IBP, but also the civilian populace. As one drives along the border road at night, the differences are quickly evident. Across the berm in Syria, nearby villages appear as clusters of bright lights while on the Iraqi side only the occasional porch light powered by a generator is visible.