Hostile ships in Tobruk harbor?

[Slitzer]

Hello, this is my first post apart from when I introduced myself yesterday English is my second language, hope you understand.

I'm playing GWX 3.0, and my crew and I was sailing into the Mediterranean Sea in the summer of 1940. My home base was Wilhelmshaven, but I went to port in Tobruk (friendly, blue port), Italian controlled Libya, because of little diesel left. Then, when I started the next patrol, all of a sudden my watch officer report [merchant sighted], twice. Italian destroyers begin to fire at two ships close to my start location. Everything happens within the harbor. Turns out the merchant ships, now ablaze, have Egyptian flags. When they are sunk, red sunk ship-icons appear at the map. I wonder, is this intentional or is it a bug? Seems a little special with enemy ships docked at a friendly port.