From FierceMobileIT:

For the first time in U.S. military history, foot soldiers and company support teams in Afghanistan are using specialized handheld mobile devices to access digital maps, exchange information with other troops and store mission-critical information. What began in 2011 as a way to supply soldiers with high-resolution maps on a PDA-type device eventually morphed into a suite of over 50 apps on something that now more closely resembles a mobile phone.

From Military.com:

In May, the Defense Department approved government-issued Apple devices using the iOS 6 operating system to connect to its networks, so long as they are operated within the confines of mobility pilots or a mobile device management (MDM) solution, once that is in place.

Likewise, the Samsung Knox version of Android was approved for use on DoD networks, pending the rollout of an MDM solution, said DoD spokesman Lt. Col. Damien Pickart.