A pluggable security device for protecting an electronic device, such as a laptop, is disclosed. The pluggable security device has a battery, a siren, and an optional accelerometer. The security device is triggered by unplugging from the electronic device, or by sensing acceleration, or by disconnecting the electronic device from AC power or from a network. Once the security device is triggered and its internal siren is activated, it can only be deactivated by reinserting the pluggable security device into the electronic device it has been disconnected from and by entering a password in the electronic device.