DLC West 45 Sealion 45

[dkm333]

I posted a picket line of submarines, cruisers, et al in front of the SW coast of England at turn 16 (one space in between the ships) with no Allied ships in sight. Yet by turn 17, the Allies had magically penetrated the picket line with transports. How is that possible?

[RPKUPK]

I had asked a similar question regarding the sudden unexpected appearance of Russian or Allied aircraft later in a battle and one of the higher ups answered and said that the AI has these units scripted in to the battle. Surprise! Perhaps the AI didn't expect you or most players to have the foresight to expect a sneak attack in that area but they appear anyway.
And, another reason could be that some of these naval units may be what I call "coast huggers" -- units hiding along the coast ready to spring forward after you have passed or missed after sudden changes in weather in areas that had just reconned clean but enemy units moved in under cover of bad weather, then, pow! Watch your weather forecast and expect the unexpected next turn.
Related, new Russian or Allied ground units can appear with strength factors of 11 or 12 or higher--they are not subject to rules of replacement of destroyed (you would have thought they must be inexperienced units with a strength of 10) units because they may be scripted reinforcements and they too can appear behind enemy lines.