This is a feature.  Maybe it started as a bug, but it's been known
since at least 1992 (check and search for declare
war).  Consider your netrek_trick_knowledge++.

On Tue, May 19, 2009 at 8:53 AM, Gremaux, Douglas A
<Douglas.Gremaux at> wrote:
> Observed on pickled server last night during pre-T entertainment.  Did not
> try it during t-mode.  While peaced and carrying, fly to enemy planet, orbit
> with shields up, and beam down.  Shields drop but armies don't, which is
> expected.  Declare war.  Armies start dropping immediately before war
> declaration 10 second timer runs out.