empty threat
idle threat

Do not make the mistake of thinking this an empty threat.

"He tried to turn things around one more time with his empty threats," she said.

Was that threat empty, or had his failure allowed it to come in its own time?

So in some ways the policy rests on an empty threat.

For a moment, as she looked into his hot male gaze, it didn't sound like an empty threat at all.

Make empty threats about what you'll do if he doesn't change.

It was an empty threat - for now, at least - but she wouldn't know that.

It was known that his were never empty threats they came to terms with him.

But she knew Adam well enough by now to know he wouldn't make empty threats.

But the practical effect of empty threats is the same.