Dear Mr. Rat,
Due to your act of defiance the other night I am afraid I must declare war. This saddens me because we had been living a peaceful existence. As long as the terms of The Contract were met everything was fine. You broke such terms when you entered into the forbidden area of my house two nights ago so therefore war is upon you and your kind.
I have brought in special forces who are known for exterminating your kind and I am confident that I have the upperhand. Unfortunately for your fellow critters there is likely to be collateral damage because of you. The special forces does not discriminate in their destruction.
So here is a farewell to our peaceful existence and to your life!