Game concept
Countermeasure Focus
The game also links it as Countermeasure Focuses, Countermeasure, Countermeasures.
From the game's encyclopedia
When you suspect that a Scheme is targeting you, you can do something about it by directing all your defenses against one type of Scheme at the cost of others.
Because of this, only one can be active at a time. Strengthening defenses in one area involves drawing attention away from another.
They can be used to reduce Secrecy or adjust the Success Chance of different groups of Schemes. They may buy you time or shore up your defenses, but come with drawbacks that mean you do not want to have one active at all times.
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Countermeasure Focus is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "When you suspect that a Scheme is targeting you, you can do something about it by directing all your defenses against one type of Scheme at the cost of others." It is part of Scheme. The game also links it as Countermeasure Focuses, Countermeasure and Countermeasures. Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/00_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.