During the same training session you advise trainee managers that the conflict management style of may be used when quick and decisive action is vital or when unpopular actions must be taken.

It seems like you're asking about a specific conflict management style that is suitable for situations requiring quick, decisive action or when unpopular actions must be taken. This style is typically referred to as the "Competing" or "Forcing" style.

Here are the steps to explain this style:

1. Definition: The Competing or Forcing style is characterized by assertiveness and uncooperativeness. An individual using this style pursues his or her own concerns at the other person's expense, using whatever power seems appropriate to win his or her position.

2. When to use: This style is effective in situations where quick and decisive action is vital - for example, in emergencies. It's also useful in situations where unpopular actions need to be implemented, such as cost-cutting measures or disciplinary actions.

3. How to use: To use this style effectively, the manager needs to clearly and assertively communicate their position or decision. They should be prepared to enforce their decision and deal with any resistance.

4. Potential downsides: While this style can be effective in certain situations, it can also lead to resentment or hostility if used excessively or inappropriately. It's important for the manager to balance the use of this style with other, more collaborative styles when possible.

5. Conclusion: The Competing or Forcing conflict management style can be a powerful tool for managers in certain situations. However, like all tools, it should be used wisely and appropriately.