Suppose an American citizen who is openly critical of governmental policy decides to take a trip overseas, say to Yemen. Suppose that President Obama orders the military and the CIA to assassinate him while he is traveling within Yemen. Suppose the order is carried out and that that American is, in fact, assassinated.
Most Americans would consider such an assassination to be a grave wrong. They might not like the criticism that the American was leveling against the federal government, but they would ardently oppose the idea of assassinating the man based simply on the fact that he was criticizing the government.