Whether or not you agree with his actions, he knew he was revealing classified information and he knew it was a crime and what the potential punishment would be.
Whether he had moral justification is a different question. Personally I don't think he did. People are cherry-picking the positive examples such as the video murder of a TV crew, but ignoring all the informants who just had their cover blown, the US's political opinions on foreign politicians and all of the rest of it.
Whatever your opinion on him, he broke the law and he needs to pay for it.
Bradley Manning is a man that wants the truths out in the public. He isn't aiding the enemy as it may seem. He is aiding the American public to find out what is really happening in the world. His efforts are against the bigoted American media who is trying to show that war is necessary and that some countries should be taken off the map. Bradley should be found innocent and be allowed to return to his family and away from all the torture he is receiving away from the eyes of the American public.
Yes, Bradley should face the punishment given to soldiers who provide classified information to places like the internet site Wikileaks. As a nation we need to keep our soldiers to a certain level of behaviors regarding this material.
His providing material such as the "Collateral Murder" video and War Diaries and Logs provided a much more important service to our nation and to the world community at large. Through this work, he brought to light the real effect on civilians of our tactics and to the American public the effect the battles have had on our collective morality.
His release of diplomatic cables had hardly any effect according to Defense Secretary Gates adding to the understanding that there was little cost to the US or benefit to our enemies.
Manning's actions did violate our laws and he must face some consequences for them. We should also honor his courageous actions for how the information made our nation face up to the realities of our actions and in the end become better because of it.
Bradley Manning released documents exposing human rights violations of the US' foreign policy. If his actions "aided the enemy," then the enemy of the US government is the people of the entire world. Bradley Manning is a hero that risked his freedom and defied his bosses to do what was right.