Please explain how these events were due to "enemy action"
Well the Hindenburg was destroyed by a bomb placed there by a group who wanted to remove some of the glory the Nazis were experiencing around the world. Unfortunately it was late arriving and so blew up before all the passangers were de-derigibled. (at least that's what this book I read said).
As for the other one, in the words of Mrs Mittleshmit "That's where my claim falls to the ground" Titanic you say. I thought it was the Lusitania.
Enemy iceberg?