Cheney wanted to use the military to round up terrorist suspects on US soil:
A decision to dispatch troops into the streets to make arrests has few precedents in American history, as both the Constitution and subsequent laws restrict the military from being used to conduct domestic raids and seize property. The Fourth Amendment bans “unreasonable” searches and seizures without probable cause. And the Posse Comitatus Act of 1878 generally prohibits the military from acting in a law enforcement capacity.
What interests me here is the fact that the task was easily within the capabilities of the FBI who did the job. What Cheney was doing here was making a point: that he believes that the president can impose the equivalent of martial law inside the country at any moment he feels it's necessary, even if it isn't. What Cheney was about was making a point about his own untouchable power outside the constitution to wage a war, even in America itself against American citizens. Remember also that Cheney strongly believes in the power of torture as well - as integral, as he has put it, to American constitutional practices.
One day, we will realize what a threat Cheney was - and remains - to America as a constiitutional republic and to the national security of the West as a whole.