SCHALAMSCHE BORDER CROSSING, Iraq – The Iranian guards stare. They sneer. They tighten their grip on their rifles.

The Americans walk past. One starts snapping photos. The Iranian doesn’t like this. He snaps and whistles, shaking his hands to stop it. The pictures are taken anyway.

Dozens of people – businessmen, religious pilgrims, tourists – walk between the two sides, apparently completely unaware of the show before them.

Welcome to the frontier.

An artillery battery from Fort Lewis is stationed several hundred yards from Basra province’s Schalamsche Border Crossing, where thousands of people and more than $2 million in goods cross daily.

Charlie Battery of 1st Battalion, 377th Field Artillery Regiment lives at nearby Patrol Base Minden and provides security for the area. Also on the outpost are an American port of entry transition team and a border transition team, each working with their Iraqi counterparts.

When Charlie Battery – part of 17th Fires Brigade, which controls the American battle space of Basra province – first arrived along the border in August, they found the Americans running the daily operations.

But now Iraqis – including policemen, border patrolmen and “border battalions” – operate from refurbished customs, immigration and health buildings.

“When we got here, this place was a wreck,” said Lt. Michael O’Brien, a Charlie Battery platoon leader from Detroit. “Since then we’ve renovated a lot of these buildings. We’ve moved into a true advise role – and usually, we don’t even have to do anything.”

During a visit last week, tour buses destined to bring Shia pilgrims to the holy cities of Karbala and Najaf idled just beyond the gate. Inside one of the passport control buildings, men with stubbly beards and women in black coverings queued to talk to an immigration official. A few killed time by texting or checking out the posters of religious shrines placed by the Iraqi tourist board.

O’Brien said the Americans have yet to have any problems with the Iranian travelers. Yet the signs of the regional instability surround the border post.

Nothing grows in the vast fields that used to be lush with date palms – and served as major battlegrounds of the Iran-Iraq war. The blue dome and orange flags of the Schalamsche memorial, a tribute to the hundreds of thousands Iranians killed during the war, sit right beyond the border. Signs warn travelers not to veer off the road because of thousands of unexploded ordnance still underground. Further in the distance, one can see the tailfins of rockets that exploded.

And American military officials have blamed the Iranian government for fueling instability in Iraq.

Iranians are infiltrating and funding insurgent groups, training and equipping fighters on Iranian soil before shipping them west, running front businesses inside Iraq to raise money for Shia extremist groups and trying to influence political development, Lt. Gen. Charles Jacoby, the Fort Lewis commander serving as the American military’s No. 2 in Iraq, said last month.

“Iranian influence permeates this entire region,” Charlie Battery commander Capt. Geoff Shorr said during the border trip last week.

Charlie Battery soldiers say the relationship between the Iranians and the Americans and their Iraqi allies on the border remains tense – but much of it is often gesturing. One barometer they use: Americans will often wave across the border and see what reaction they receive.

“If you get one of them one-on-one when his pals aren’t looking,” O’Brien said, “they’ll usually wave back. They’re just guys with jobs to do too.”