Late last month, officials from the Army and from Boeing presented to the press what appeared to be a working version of a mobile laser cannon. Parked in front of an American flag was an eight-wheel, 19-ton heavy truck. Affixed to the top of that truck was a laser-beam controller, used to aim and fire lethal rays of coherent light.

There was only one thing missing from this $38 million High Energy Laser Technology Demonstrator: the laser itself.

The actual ray gun is being built under an entirely separate Army program — one that won’t be complete for another five years. Integrating the truck and the laser could take another year or two on top of that. In other words, don’t expect a working laser cannon until at least 2017.

The Pentagon devotes about $550 million annually to a mind-bending myriad of research-and-development projects, all designed make lasers and other so-called “directed energy weapons” a reality. Some programs are for lasers tucked into bombers, like Darpa’s High Energy Liquid Laser Area Defense System. Some are for ships. Others are for trucks.

But they all have a common denominator: the blasters are still far from combat-ready. At this rate, even the interminable Afghanistan war could well be over before America has any semblance of a ray gun arsenal.