Persistent Threat

Definitions

A threat actor or campaign characterized by maintaining access, returning repeatedly, or operating over a long period instead of acting once and disappearing. The phrase is often used when attackers show patience, operational discipline, and a goal beyond quick smash-and-grab activity.
In plain English: A threat that stays active over time instead of attacking once and leaving.
Example: "This looked like a persistent threat because the operators restored access twice after partial containment and kept focusing on the same research data."