WASHINGTON — The Islamic State group is increasingly using improvised explosive devices as front-line weaponry against coalition forces in Iraq and Syria, a top US general said Friday.

Marine Corps Brig. Gen. Thomas Weidley, chief of staff, Combined Joint Task Force - Operation Inherent Resolve, told reporters on a Pentagon conference call that the militant group, also called ISIL or ISIS, has taken to using IEDs the weapons, known as IEDs, in much the same manner the US employs high-end strike weaponry.

"Obviously [IEDs have] become the precision guided munition [PGM], if you will, for [ISIL]," Weidley said. "We see them, again, as one of their primary weapon systems in order to disrupt, in order to penetrate [Iraqi or Kurdish] lines."

Obviously, an IED does not have the same high-end targeting that a PGM has. But the advantage for ISIL, in that comparison, is cost. On June 16, the Pentagon put the total cost of anti-ISIL operations at $2.74 billion, or an average of $9.1 million a day – staggering figures given that ISIL continues to have success in the region.

Part of that cost is targeting the source of IEDs, with Weidley saying the government is actively hunting for production sites.

"It is a very effective weapon and we have taken great efforts to advance our targeting capabilities in order to allow us to find these locations where IEDs are being produced and target them appropriately," he said.

In the meantime, the US is attempting to combat the use of IEDs by expediting the flow of anti-tank munitions to Iraqi security forces.

The fact that anti-tank equipment is effective against IEDs shows how the threat has changed. Where IEDs were largely seen as traps over the last decade, ISIL is increasingly using large vehicles strapped to explode as, essentially, missiles aimed at government forces on the ground.

Speaking last week, Brett McGurk, deputy special presidential envoy for the Global Coalition to Counter-ISIL, said the militant group has begun using large trucks rigged as suicide bombs as its "weapon of choice."

In particular, the US is expediting the movement of AT4 shoulder-mounted weapons to Iraqi forces to help take out those incoming trucks. If truck-based IEDs are incoming missiles, think of the AT4 as the Iraqi security forces' version of a missile defense program.

"We've already seen instances of them using these weapons to great effect," Weidley said.

However, ISIL is continuing to evolve its tactics, something Weidley hinted at later when asked about the group's use of tunnels under Iraq.

"We do see tunneling as a technique that [ISIL] uses. We see them use it, not only to move equipment and fighters, but we see them used as IEDs, a tunnel IED. We saw that in Ramadi," he said.

Twitter: @AaronMehta