An Islamic State car bomb seconds before exploding (Image from Islamic State video)

As Iraqi troops slowly push into Mosul, backed by heavy airstrikes, artillery and Western advisers, the Islamic State is fighting back not only conventionally but also with slick propaganda footage showing its prowess on the battlefield.

A 26-minute video, posted Monday, has all the hallmarks of Islamic State films of its summary executions: high-definition footage and solid production. The video also uses drone footage to show the charred wreckage of Iraqi military vehicles and the U.S.-supplied equipment that the group plucked from them.

Militants appear to drag a U.S. grenade launcher from the wreckage of a destroyed Iraqi Humvee. (Image from Islamic State video)

Although past Islamic State videos may have shown the group’s battlefield victories, this video — while playing up small tactical successes — seems to exist to show that it is fighting tenaciously to hold Mosul even in the face of overwhelming force on the other side, including U.S. air power.

What also sets the footage apart is the dozen or so segments that show how the Islamic State is using vehicle-borne improvised explosive devices, or car bombs. It is unclear how many of the explosive-packed suicide trucks the Islamic State really has, but as the battle for Mosul enters its second month, it appears the group is well stocked — and is using them almost daily.

The group uses car bombs to spearhead offensives, harass advancing troops and cover retreats, and it has become a key tactic to counter a well-supplied conventional military.

As Iraqi troops, including the Golden Division, an Iraqi special-forces unit, approached Mosul, they had the advantage of the open desert to detect and respond to incoming car bombers. Tanks and U.S. aircraft could easily target the vehicles.

During the Iraq War, suicide bombers could be stopped by shooting through the driver’s windshield or disabling the engine with machine gun fire, but — as seen in the video above — Islamic State machine shops have turned civilian vehicles into armored monstrosities. These hulks are capable of carrying large amounts of explosives while protecting the driver from an array of shoulder-fired threats, from small arms to rockets.

The threat of car bombs has been the driving force behind many of the weapons requests for U.S.-backed forces on the ground fighting the Islamic State. Peshmerga fighters have hailed the German-supplied MILAN antitank guided missile for its ability to stop the car bombs, and the United States has shipped thousands of U.S. AT-4 84mm shoulder-fired antitank missiles to the Iraqi military.

But these weapons, along with the large high-caliber guns mounted on armored vehicles, take time to aim and fire. Rockets need to be sighted in and, because of the shock wave created when they are fired, can’t be used just anywhere. These factors, compounded by the dense urban sprawl of Mosul, have created a nightmare scenario for Iraqi troops entering the city. Suicide vehicles spring from back alleys and cut in and out of side streets before striking Iraqi vehicles.

Iraqi forces say they have retaken a neighborhood in Mosul from Islamic State militants. (Reuters)

The speed of the car bombers and an urban environment packed with civilians have made airstrikes against them almost impossible. Col. John Dorrian, spokesman for the U.S.-led campaign against the Islamic State, confirmed the problem, saying that the deeper into the city the Iraqis get, the harder it is for U.S. air power to stop the suicide vehicles.

In the footage posted by the Islamic State, the car bombers appear to be surgical in their approach. In one instance, a bomb-laden truck drove past three Iraqi Humvees in favor of hitting a much more concentrated group a hundred yards up the road. In another, the suicide vehicle bypasses an armored Iraqi bulldozer trying to block the road by going up on the sidewalk, only to explode behind it.