The Vietnam War demonstrated the problem with governments keeping the majority of the war secret from the public. When the reason for war is clear (Germany invading Europe, Japan invading Asia, Saddam invading Kuwait, clearing al Qaeda out of Afghanistan) the government doesn't necessarily need to have that many secrets from the public. When you have a war like Vietnam and Iraq, now you have a government lying to the public because the public would not otherwise be behind the leaders' decisions to carry on these wars.
And, when war is not going well, or is not clean which happens when the enemy and the people on your side are from the same country, there are sadly many things the public wouldn't likely tolerate.
These are not legit reasons to hide the truth from the public under the lie of 'troop security'. When these things come to light they are more likely to stop. It is our tax money and our soldiers dying in these wars. Only a few of the people making decisions have any family or loved ones taking the bullets and bombs for everyone. The public has a right to know. And if the Pentagon and government were honest with the people, Wikileaks would not be dumping documents for us to see. There would be no need.
Everyone should watch
the documentary on the Pentagon Papers or read
the book if they haven't already.
Keep in mind that the SCOTUS ruled the Papers could be published, and a member of Congress read the Papers into the Congressional Record to thwart suppression of the information getting out.
NYTs summary of the events.