Backblast From the Past:

Watch enough YouTube videos of the fighting in Syria, and you’ll start to notice it: a long-tubed gun, mounted on the back of either a jeep or large, fast pickup. Usually it’s blasting bunkers, blockhouses, fortified positions, or places where snipers are hiding. It even goes after tanks. And whenever it fires, the gun seems to kick up way more hell behind it than what it sends out the barrel’s front end. It’s the M40 106mm recoilless rifle, an American-made, Vietnam-vintage weapon that got dropped from the Army and Marine inventory back during the early 1970s. Until recently, the 106mm hadn’t seen much action in the irregular wars that have swept the globe. Then M40s somehow came into the hands of rebels in Libya and Syria. Suddenly, the 106mm - light, cheap, easily transportable, simple to operate, and packing a punch all out of proportion to its modest size — has emerged as a possible Great Asymmetric Weapon of the Day.

Although the U.S. military no longer officially uses the M40, they still keep some around. A few found their way to Afghanistan where they were put to use by certain Special Forces units. The Danish and Australian armies, which acquired them from the U.S. decades ago under the Foreign Military Sales (FMS) program, used them extensively during their ground operations there.

In Libya, the M40 was used primarily in urban warfare, killing tanks and fortified positions. How exactly it found its way into the hands of the rebels there is a bit of a mystery. The M40s showed up in Libya along with thousands of brand new Belgian FN rifles, apparently from Western arsenals. That lead many to suspect they were supplied by Western intelligence. The M40s currently being seen in Syria might be coming either from the same sources that supplied the Libyan rebels or even from the Libyans themselves.

There is also a strong possibility that these weapons might actually be of Iranian origin. Iran’s state-owned weapons arsenal, the Defense Industry Organization, has been manufacturing what was originally a licensed-version of the M40. Now called the “Anti-Tank Gun 106,” it is being offered on the open market, and are probably being supplied to the Syrian Army, which have since lost them to the rebels.