Never permit the enemy to acquire an unexpected advantage. Monitor competitors and stay vigilant.

During planning processes it is often necessary to maintain secrecy to gain surprise. In many societies, the proverbial wisdom is that "the walls have ears, the doors have eyes". The Japanese proverb is "Kabe ni mimi ari, shoji ni me ari" meaning one may not be fully aware of how closely one is being monitored by others. Planners should take precautions to insure that only those who should know about the planning process and situation and the plans, do know.

"Spies cannot be usefully employed without a certain intuitive sagacity; They cannot be properly managed without benevolence and straight forwardness; Without subtle ingenuity of mind, one cannot make certain of the truth of their reports; Be subtle! be subtle! and use your spies for every kind of warfare; If a secret piece of news is divulged by a spy before the time is ripe, he must be put to death together with the man to whom the secret was told." - Sun Tzu quotes

from http://encyclopedia.thefreedictionary.com/Japanese%20proverbs
http://www.military-quotes.com/