Us Sub Mission 9, Friendly Fire Between Enemy Ship

i was chasing the oilers, but the enemy ships were fring on each other until every of them sank. Whats going on? AIs made friendly fires? They were all red dots appearing on my screen by the way.

Could have been a combination of 2 enemies (check the orders...)

Usually helpful to say which mission .

e.g.. LFN - sub - 5 ::: Faction-sub or surface - number

Yes there is one mission most or all enemy will destroy each other if you keep quiet long enough , and finish off the last .

It doesn't always work out that way so easily tho !