Tunnel bombs are not a bad-guy epiphany, but a natural manifestation of the battlefield. Yet as many tactics are eventually exported in attacks on the West; should we be looking underground for the next massive attack? Yes.

Another historical replay, labeled “new” by people who only reference history in a ‘today’ context has been underway throughout Iraq and Syria. As militants and terrorist alike look for new ways to break through hardened defensive fortifications and obstacle belts – they’ve opted for the road less traveled, underground.

The onset is not some breakthrough in guerrilla warfare. In fact, the concept is as old as siege warfare, when the Sappers of yesteryear, in Roman and Medieval times, would tunnel underneath castle and fortification walls to denote a charge, or remove the supporting earth to force a breach and/or destabilize the walls for an effective artillery or catapult fire breakthrough. In more modern times, tunnel warfare, along with the deployment of hill mines that ripped the soil and lives from the stagnant lines of World War One. In Vietnam, tunnel warfare was rampant and manifested into a uniquely vicious form of killing. Throughout the Afghanistan and Iraq Wars; deep buried improvised explosive devices were favored amongst insurgents who sought to challenge heavily armored allied vehicles.

The tunnel bomb is not something new, and is clearly not outdated. Yet the reemergence of tunnel bomb tactics on today’s international battlefields across the Middle East should raise concern and merit a plan of deterrence from intelligence and security agencies.