A Web browser (210) is configured to run in a middle compartment (206) of a Compartmented Mode Workstation (CMW) (200). The operation of the Web browser (210) is prevented from accessing or damaging other compartments of the CMW machine (200) as a result of mandatory access control (MAC), which is configured appropriately. The Web browser (210) communicates with Web servers (252) attached to the internet (240), the Internet being connected to an outside compartment of the CMW machine (210), via a trusted outside process (TPO) (214). TPO (214) has the privileges required to override MAC. The Web browser (210) communicates with a display server (232), which is attached to an inside compartment (204) of the CMW machine (210), via a trusted inside process (TPI) (204). TPI also has privileges to override MAC. The Web browser (210) can request and receive Web pages incorporating mobile code, and can process the mobile code safely within the middle compartment (206). As a result of processing the mobile code, the Web browser (210) sends only X-messages to the display server (232), in order that the display server can render the images resulting from the processed mobile code.