Alongside the HTC-made handset are an altitude and orbit control system, two propulsion setups and a Linux-based computer with a "high-speed" processor.

ENGADGET

And what - we can't leave out the terminal phase of missile defense, which is things like PAC-3, the Patriot Missile System, and the Terminal High Altitude Area Defense or THAAD, which would shoot down on a threat missile in the final phase of its flight.

NPR: Missile Defense, the U.S. and Europe

To combat this threat, aircraft have a warning system which alerts the crew if the cabin altitude is approaching dangerous levels.

BBC: NEWS | Europe | Dangers of aircraft decompression

Using ATOP, if a pilot requests an altitude or route change, the system loads the new information, based on the data transmission from the plane, calculates any possible conflicts and suggests responses from the controller automatically.

WSJ: How New Air-Traffic Control Systems Operate Over Oceans

The U.S. military has positioned its Terminal High Altitude Area Defense (THAAD) missile defense system and its X-band radar system in the event a missile were to be launched toward Hawaii.

CNN: U.S. dismisses latest missile provocation by North Korea

It is developing a surveillance system funded by several U.S. government agencies based on an unmanned plane that will fly at an altitude of 11 miles (versus 22, 000 miles for a satellite) and stay aloft for a week at a time.

FORBES: Companies, People, Ideas