Why do we have wmds? Please answer pro-wmd reasons.?

If you think about the old Slogan, "Speak softly and carry a big stick." Now think of todays times. Do you really think of all the Middle Eastern countries that would be more than happy to wipe America off the face of the earth, and you can honestly say we don't need them? Biological weapons and (Lethal)Chemical Weapons are illegal, as far as I'm aware.