In Afghanistan, IEDs (Improvised Explosive Device, a roadside, or suicide car bomb) now cause over 70 percent of NATO casualties. It has also been discovered that there was one big difference between the IEDs in Iraq and Afghanistan; the explosives used. In Iraq, there were thousands of tons of munitions and explosives scattered around the country after the 2003 invasion was over. This was the legacy of Saddam Hussein, and the billions he spent on weapons during his three decades in power. The Iraqi terrorists grabbed a lot of these munitions, and used them for a five year bombing campaign.
With no such abundance of leftover munitions, the Taliban had to fall back on a common local explosive; ammonium nitrate. This is a powdered fertilizer that, when mixed with diesel or fuel oil, can be exploded with a detonator.
I long held that the relatively small insurgency in Iraq was powerful out of proportion to its numbers because it had money and weapons inside Iraq to finance the terror and attacks. We didn't really need to waste troops and resources guarding the border since few weaponry had to enter Iraq to fuel the insurgencies and terror.
Since the Taliban need this imported raw material to build IEDs, we have a reason to control the border as much as possible. Add this to imported gunmen and weapons and you have more reason not to abandon the border and pull back to the cities and villages to defend them.
On the bright side, our casualty rate (and civilian victims of the jihadis) should be much lower in Afghanistan than in Iraq at the height of the fighting.