THREATEN

[verb]The man threatened revenge on the police. [T]They threatened the shopkeeper with violence/a gun. [T]They threatened to kill him unless he did as they asked. [+ to infinitive]Look at those clouds! There's a storm threatening. [I]The weather threatens to change by the end of the week. [+ to infinitive]Changing patterns of agriculture are threatening (= causing damage to) the countryside. [T]