This section of the research guide focuses on the most disruptive and potentially destructive types of cyber attacks—those that target critical national infrastructure (power grids, air traffic control systems, banking networks, etc.), which may qualify as armed attacks or acts of war under international law. Such acts are characterized as cyber warfare when perpetrated by state actors and as cyber terrorism when perpetrated by non-state actors. A key consideration in deciding how to respond to such an attack is determining who is responsible, known as the problem of attribution.