I pretty much agree with Ken's comments.

On the border, we can probably do a better job of interdiction, but one complicating factor is that a lot of people besides insurgents use the border. Some are insurgents, some are smugglers, some are doing legitimate trade, some are visiting family, etc. Even if it were possible "closing" the border is going to have some significant negative effects. Sorting legitimate border crossings from insurgent use is going to be difficult given the terrain and all the other complicating factors.