President Obama has spoken publicly about the importance of government transparency and protecting whistle-blowers. By sharing sensitive military documents with Wikileaks, Bradley Manning made public military abuses perpetrated by the US military. Instead of being praised for his patriotic actions, Manning has been held in solitary confinement for months prior to his trial and has now been found guilty of espionage and other serious crimes that may earn him a life sentence of imprisonment.
This sets an extremely discouraging precedent for people currently aware of illegal activities who might be considering becoming whistle-blowers.
More importantly, this against the fundamental principles of the United States of America.