What term expresses an increase of troops or other military units in a standoff between two armies, when no actual fighting has yet occurred? Specifically, I'm looking for something in the context of a naval battle. 

For land-based tactics, I've heard *massing of troops*, but what is a better term for a conflict at sea?

**EDIT:** Ideally, I'm looking for a verb:

> 
> The warships were *VERB*-ing
> 
> 
>