In what could be yet another huge blow to Apple’s falling stock prices, the U.S. government’s Department of Defense has approved the use of Samsung Galaxy S4 and BlackBerry Z10 within Pentagon, while it still waits to sign off on Apple’s iOS 6.

This means that DoD employees can choose to use the Samsung Galaxy S4 or BlackBerry Z10 as enterprise mobile devices and connect to the DoD networks to access their work. It’s a huge market share – there are at least 600,000 mobile device users in Pentagon. Among these, BlackBerry accounts for the lion’s share of over 470,000 users, followed by 41,000 Apple users, while Android ranks a distant third with just about 8,700 takers.

But thanks to Samsung’s Knox, which is a secure version of Android, the tables could possibly turn in favor of the Galaxy S4. Knox was developed in collaboration with the NSA, making it an even more appealing option from a security standpoint. With multiple layers of security, it lets Galaxy S4 users set individual privacy levels for each app on the device.