A portable security system for monitoring an asset has one or more alarm sensors and a wireless transmitter/receiver that communicates via wireless communication with a host system. The portable security system is switchable between a disabled (partially powered) state and an enabled (fully powered state) in response to commands received from the host system. In an aspect, the portable security system has a plurality of alarm sensors which a user can separately activate and deactivate via the host system. In an aspect, the portable security system includes a base unit and an auxiliary unit. The base unit includes one or more of the alarm sensors that serves a dual purpose depending on whether the base unit is mated with the auxiliary unit. In an aspect, the host system can be utilized by multiple users to manage portable security systems associated with the respective users, including management by group. In an aspect, the host system notifies a user(s) of an alarm condition(s).