Zurbatiya, Iraq ? The U.S. colonel had a simple question.

“Where are the signs you were supposed to get?” he asked the Iraqi border guard as they stood on a remote desert road believed to be a smuggling route from Iran.

The Iraqi officer pointed his flashlight at three signs that were intended to alert motorists to checkpoints. The signs were lying on a mound of sand.

“Why haven’t you put them up?” Col. Mark Mueller asked during a late-night inspection. “All you have to do is pound the stakes into the ground.”

But, the Iraqi explained, he didn’t have a shovel.

Such are the obstacles facing U.S. soldiers as they increase training of Iraqi border guards in this sparsely populated mountainous area southeast of Baghdad, believed to be a major route for weapons and fighters slipping into the country from Iran.

The former Soviet republic of Georgia sent 2,000 troops to help last month, but they haven’t yet left a major base in the area. Mueller and his troops also are getting a late start, basically trying to secure the thinly patrolled border from scratch after it was largely ignored during more than four years of war.

The area has attracted new U.S. attention as the military steps up allegations that Tehran is aiding Shiite extremists who have killed hundreds of American troops with powerful bombs known as explosively formed penetrators, or EFPs, believed to be brought in from Iran. Tensions between the two countries also have been rising over Iran’s nuclear program and the recent detentions of each others’ citizens.

Mueller, 48, from Yorktown, Va., is the commander of the 3rd Infantry Division’s border transition team at the heart of an intensified U.S. push to stop the smuggling. The strategy is similar to American efforts elsewhere in Iraq – build up the infrastructure and train the Iraqi forces to take over eventually.

The 900-mile border between the two countries, however, is laced with ancient smuggling routes and tribes who spent decades bringing in weapons to fight Saddam Hussein’s regime and are now believed to be making their living from Shiite militias. The problem is particularly stark along the 90-mile section in predominantly Shiite Wasit province, southeast of Baghdad.

Mueller acknowledges the virtual impossibility of securing such a border but says the U.S. forces can at least disrupt the flow of weapons into the capital.

The centerpiece is a plan to build a new base to house some 100 Georgian troops and as many as 66 Americans just four miles from the Iranian border.

Commanders said the facilities – complete with Internet access, electricity and housing – will enable the troops to spend every day at the border. That’s an improvement over making the dangerous, 50-mile commute in convoys from their regional hub near Kut, a violence-ridden city of 350,000.

Maj. Toby Logsdon, 34, of Litchfield, Ill., who is overseeing the $5 million project, said the aim is to have it operational by November.

But he conceded the deadline may be overly optimistic. He stood on a watchtower at an adjacent Iraqi base and pointed to a 150-by-300-yard patch of empty desert with no sign of development except for two working gravel pits in the distance.

The problem has roots in the immediate aftermath of the 2003 U.S.-led invasion, when the American military was focused on seizing Baghdad. The U.S. Marines received orders to send patrols to the area southeast of Baghdad – but not to the frontier itself, despite fears it was a tempting entry point for Islamic militants from Iran.

The Iranians took advantage by building a concrete wall separating the two countries at one of four border crossings. The wall blocked views of the trucks being searched and their cargoes loaded into Iraqi vehicles on their territory.

Iran denies it is stoking violence in Iraq, but there’s no doubt that Shiite-dominated Iran’s influence on trade and politics over the border has grown since the toppling of Saddam’s Sunni-dominated regime. That has the U.S. nervous.

Maj. Gen. Rick Lynch, who commands U.S. troops south of the capital in a bid to block the flow of weapons and fighters into Baghdad, said last month that his troops were tracking about 50 members of Iran’s Revolutionary Guard Corps in their area – the first detailed allegation that Iranians have been training fighters within Iraq’s borders.