Which word refers to actions that are carefully planned to cause disruption?

The term that best fits the description of actions that are carefully planned to cause disruption is "sabotage." This word specifically refers to deliberate acts designed to damage, hinder, or obstruct an effort or process. Sabotage often involves calculated steps, typically executed in secret, to undermine a system, organization, or project.

In contrast, "intrigue" refers to the creation of secret plots or the quality of being fascinating; it does not specifically imply disruption. "Perfidy" denotes deceitfulness or untrustworthiness, often in terms of betrayal, rather than a direct act of disruption. "Conspiracy" involves a collaborative plan to achieve an unlawful or harmful objective but may not always imply actions that disrupt existing systems. While "conspiracy" can potentially lead to sabotage, it is broader and does not exclusively focus on acts of disruption.