The Department of Defense is moving forward to adopt civilian wi-fi wireless networking. The Pentagon held off on wi-fi for some time because of security concerns. Wi-fi comes with feeble security (weak encryption), which many civilian users don't even bother to turn on (because is slows down transmissions a bit). But the Department of Defense has been able to get stronger encryption, from civilian firms, for military wi-fi networks. This type of networking has obvious advantages for the military, because the troops often operate in the field, where it is difficult to use cabling required for conventional networks. Even on ships, like aircraft carriers, wi-fi is more practical. Aircraft have to have their navigational and fire control systems updated before take off, and mission data offloaded after a flight. Wi-fi makes this easier than using tapes. Marine amphibious vehicles also have computers that need data updated before they go ashore. Wi-fi makes this much easier than using cables or tape drives, especially because of all the salt water (and subsequent corrosion) amphibious vehicles are prone to. Air force have the same data transfer needs as carrier aircraft, and army units are particularly in need of wireless networks.