For now

"Do not worry, loyal citizens. There is absolutely no reason to think that your planet is facing imminent doom...for now."

- Darth Vader to the hippies of Alderaan

For now was a phrase used by certain Sith Lords that served as a sort of addendum to whatever agreement or statement they had just made.

Usage
Usually, a Sith Lord would utilize this convenient phrase when promising not to destroy a planet. The overall effectiveness of the phrase was due mostly to the dual layers of evilness with which it was associated. As it could be tacked on to the end of pretty much any statement, the fear of hearing it from a Sith was usually enough to force submission from most victims.

The tone with which it was delivered also served the dark tendencies of those Sith that utilized the phrasing, as well. A short pause and then inclusion of the addendum versus an immediate citing of the words usually meant the difference between life and death for those dealing with the Sith.