It's very useful to know foreign languages. We are wrong when we say, that animals don't know other languages. The excellent example is this cat. She barks like a dog, but when her owner comes she stops the barking and continues with meowing. The ability to "speak" is something that is kept in deep secret from the humans, because the cats prefer to live lazy life. It's like the swimming - Cats hate water and show us that they don't like it. But sometimes they enjoy it and also swim!
So don't be surprised to understand, that the kitties already know the language of their enemy! :)