"'I am against you,' declares the Lord Almighty. 'I will lift your skirts over your face. I will show the nations your nakedness and the kingdoms your shame. I will pelt you with filth, I will treat you with contempt and make you a spectacle. All who see you will flee from you and say, "Nineveh is in ruins - who will mourn for her?" Where can I find anyone to comfort you?'" NIV translation
The name "Lord Almighty" speaks of the fact that God created all and therefore owns all things and can provide all things. For the reasons that God listed, He says that He is going to expose the people for what they have done. As Creator, He has the right to do so and intends to make an example of them to the nations. Imagine holding a funeral service for someone that nobody believed was dead and you get a picture of what God is saying here. None of the other nations would have believed that the great Assyrians could be humbled but, once it is revealed, their friends will run like rats leaving a sinking ship.