Photo via Raytheon

The Washington region has some of the country’s most restricted airspace, and defense officials are always seeking ways to better protect the government and military installations in and around Washington. Soon they’ll start relying on a hi-tech adaption of a decidedly low-tech option: helium-filled blimps. Reports Reuters:

A pair of big, blimp-like craft, moored to the ground and flying as high as 10,000 feet, are to be added to a high-tech shield designed to protect the Washington D.C. area from air attack, at least for a while.

The bulbous, helium-filled “aerostats” – each more than three quarters the length of a football field at 243 feet – are to be stitched into existing defenses as part of an exercise of new technology ordered by the Defense Department.

The pair of blimps—known as JLENS—will cost $450 million and could see airtime as soon as September. They can each see 340 miles down the horizon, alerting the military to any potential threats to the National Capital region. Raytheon argues that the blimps are substantially cheaper than having airplanes patrol the skies above the region. Blimps are being used more and more by the military, including in war zones.

For all the technology that goes into the blimps, though, here’s a weird little twist: each blimp is tethered to mobile moorings on the ground.