WWII Propaganda

What I think the poster, "Keep your 'trap' shut! Don't give the rats any information!" means is that if bystanders during WW2 said anything along the lines of their goverment's war plans they would be hurting their nation. As you can see in the poster there is a mouse trap and a piece of newspaper caught in it. They usually referred the enemies as rats. The newspaper was a part of an article that was about a ship sinking due to being attacked. What the image implies is that if you carelessly talk about your governments war plans you could potentially cause an attack. This tries to scare its citizens by showing that they're the causes of other countries attacking them because they don't keep their "traps" shut. I feel that this propaganda piece is just trying their citizens to fear them and potentially obey their laws.