Since 2010, there have been four incidents of vandalism at SMRT depots. Each incident revealed security vulnerabilities which were quickly addressed. Since then, patrols have been intensified and fence intrusion detection systems, extra perimeter lighting and closed-circuit television systems were progressively installed in and around the depots. Security operations were also consolidated under a single provider to enhance depot security. While the defacement of the trains meant that they had to be removed from service for up to a week to be cleaned, we were more concerned with the illegal entry into our depots as such breaches could compromise commuter safety and security. We have been working closely with the security agencies on effective ways to determine, deter, defend and defuse potential threats.