This might need further testing it happened when I used the Stink Pot the first couple of times mid fence, but others it didn't make the Navy go through. I continued to work it and standing further from the fence appears to make the Navy come through, closer to the fence didn't.

Also I had my first encounter with one of the new "Bosses". A Veteran Boss, by the name of Sid Shivers (level 18) with a red skull over his head. It took 10 direct hits from and explosive grenade to take him down and I got 49 points from it. I'm currently a level 18 on the nades with two points in explosive so these new bosses will be a challenge.