In December the Air Force admitted dumping the incinerated remains of almost 300 U.S. troops in a Virginia landfill, which doesn't really qualify as an unswerving commitment to preserving the dignity of the dead.
Still, stealing secret files from your employer and giving them to WikiLeaks where they can be published with the specific intention of embarrassing your employer and inciting public rage against it is illegal pretty much anywhere.
Both Manning and the P****ng Marines are subject not to civilian laws, however, but to the Uniform Code of Military Justice (UCMJ) which varies in odd ways from civilian rules.
One is the ability to prosecute service members for archaic crimes like Dueling long after civilian laws would have to break down the duel into assault and weapons charges to build a prosecution.
Another is the criminalization of anything that might erode the order, efficiency or discipline of the military.
(Look around your office right now and think how many colleagues you'd like to send up on charges of Malingering or Disrespect Toward a Superior?)
The UCMJ also has a trump card, Article 134, which makes anything a crime the military thinks should be prosecuted as a crime.
Sometimes called the "Devil's Article, according to Wikipedia, Art. 134: General Article covers "all conduct of a nature to bring discredit upon the armed forces and crimes and offenses not capital of which persons subject to this chapter may be guilty."
Under normal conditions disrespect toward a dead enemy on the battlefield during wartime wouldn't come close to qualifying.
For example, during World War II mistreating dead enemies was so widely accepted that even stealing body parts was common. In the May 22, 1944 issue of Life magazine showed a picture of a Navy lieutenant's girlfriend writing a letter the caption claims is a thank you for the Japanese skull he'd sent her.
In a memoir of his time fighting in the Pacific during World War II, Eugene B. Sledge described life in combat with details that were more gruesome to readers because they were obviously routine for participants.