Often conservatives (and hawkish liberals like Hillary and Biden and Lieberman) justify the need for secrecy in foreign policy. The following is a great answer to that justification from 17th century Jewish philosopher Baruch de Espinoza (better known as Spinoza).
It has been the one song of those who thirst after absolute power that the interest of the state requires that its affairs should be conducted in secret…But the more such arguments disguise themselves under the mask of public welfare, the more oppressive is the slavery to which they will lead…Better that right counsels be known to enemies than that the evil secrets of tyrants should be concealed from the citizens. They who can treat secretly of the affairs of a nation have it absolutely under their authority; and as they plot against the enemy in time of war, so do they against the citizens in time of peace.
I write this not only as an indictment against the justifications that are constantly heard from the Cheney administration, but as a warning regarding both Hillary Clinton and Rudy Giuliani. Both are well known for their secrecy and authoritarian streaks. Giuliani is especially to be watched and kept as far from power as possible, unless you want to be enthralled to the government that is supposed to protect your rights, not take them away.