A threat can be an unwanted (deliberate or accidental) expression of intent to execute action that may result in harm to an asset. The threat can have a form of an explicit or implicit message.
Another meaning of a threat is a person who is regarded as a danger. Often, the threat is exploiting one or more known vulnerabilities.
Examples are a robbery, kidnapping, Hijacking, extortion, or blackmail.
The message may be vague and implicit in an attempt to avoid blame, including legal consequences, while still clear enough to serve its purpose.
The 1969 Vienna convention on the Law of Treaties notes in its preamble that both the threat and the use of force are prohibited. Moreover, in Article 52, it establishes the principle that if threats of using force are made during diplomatic negotiations, then any resulting treaty is invalid, stating "A treaty is void if its conclusion has been procured by the threat or use of force in violation of the principles of international law embodied in the Charter of the United Nations."