As critical supply chain cybersecurity threats increase, so does the importance of a systematic supply chain cybersecurity management strategy. Managing risk factors in the supply chains is particularly important to ensure the safe, reliable, and secure operation of critical systems such as infrastructure, cyber-physical systems, and industrial control systems, whose breach can extend to significant physical, economic and environmental damage. This paper presents case studies of thirteen supply chain cybersecurity management practices from public and private industrial sectors, and an exploratory trend analysis. The case studies concentrate on the practices of critical system operators in managing the security of their suppliers from a comprehensive supply chain cybersecurity risk management perspective. While the thirteen cases are not representative enough to draw clear trends, the results of the exploratory trend analysis are still valuable in that they provide insights for organizations operating critical systems to formulate supply chain cybersecurity management strategies and plans.