The SolarWinds hack is a typical APT attack, says Julian Zelizer. It has targeted several US federal departments, private companies and critical infrastructure organizations. Zelizer: Cybersecurity relies on timely detection that minimizes damage through appropriate response and recovery. Security can only be seen from a holistic point of view and not in isolation, Zelizer writes. The identification and protection aspects of cybersecurity in this particular case focus on the supply chain, not excluding internal system vulnerabilities, he says. Supply chain cybersecurity should be addressed not only through contractual agreements but through continuous testing and monitoring.”]