Yes, you may be detained by the military if you are suspected of terrorism, however I feel with the current state of international terror this isn't too extreme. You would not be held without extreme confidence, as it would be a terrible PR nightmare if somebody is unfairly held. It is a matter of national security, which our country has done an excellent job doing since the 9/11 attacks.
Not a single plane has been hijacked since TSA was formed, and every attempt of terrorist activity on our homeland has been thwarted by US intelligence and standard operating procedures.
You should thank your government. I feel safe, and while I don't agree with every gov't decision, I am proud to be a citizen of a country where the government has taken such steps to secure my safety.