Playing DA 1.59(more numbers). I was the Altarians at war with the Drengin. I was blockading all the Drengin worlds. I had eye of the universe and advanced espionage on the Drengin. I knew the Drengin fleet was down to six gifted ships all many weeks away. I offered a peace treaty to the Drengin for all their bc's and ip's. They accepted and I clicked send. I then clicked declared war, clicked send, and clicked done. The end of turn report reported the peace treaty and war declaration.

Here's the bug:
At the beginning of my next turn and right next to Drengi appeared three or four stacked fleets of their mass driver small hull, of the Drengin current best design, each fleet to their max logistics possible.

Humor only:
  
I have other theories:
- David Copperfield was performing on Drengi and made the ships reappear at the end of his show.  
- Time space continium phenomenon, like a worm hole.  
- They jumped in from another part of Drengin space not on this particular map, or were left over from another scenario and decided to show up now.   
- The Romulans shared their cloaking technology with the Drengin empire. I think it was dumb for them to share it with the Klingons in the first place.   
- This is already a Drengin ability that I have overlooked.   
  
Thanks in advance.