US Constitution Article 3 Section 3. Treason against the United States, shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort. No Person shall be convicted of Treason unless on the Testimony of two Witnesses to the same overt Act, or on Confession in open Court.

On Sept 20th, 2001, George W. Bush announced a "war on terror". "Our war on terror begins with al Qaeda, but it does not end there. It will not end until every terrorist group of global reach has been found, stopped and defeated." http://www.whitehouse.gov/news/releases/2001/09/20010920-8.html

If we are engaged in a war on terrorist groups, then anyone who gives aid and comfort to terrorist groups is an enemy.

One major aim of terrorist groups is to get hold of weapons of mass destruction, in order to better terrorize a target population, such as the people of the US.

At the time Bush gave his speech, Valerie Plame was an undercover CIA agent, running an international ring of CIA assets, whose job was tracking WMD's through world black markets and preventing them from falling into the hands of terrorists. Two years later, her undercover identity was leaked to the press. Her outing did serious and lasting damage.