Arens has good advice. Don't bark unless you follow up with a big stick. In the past he says that there were barkings but the sticks were never followed. Hence, the savages were emboldened to carry more attacks on Israel leading to the recent war. And the performance was not impressive. He may be alluding to the fact that an empty drum makes a loud noise. There is a lesson to be learned here. You would certainly keep certain things behind closed doors but always be prepared with a big stick. Begin and Sharon certainly knew this prior to Osirak.
IDF strikes Gaza targets in response to rocket fire (Haaretz)
from the article: Good advice from Confucius