It means, “Let him who desires peace prepare for war.”
The idea of peace through strength was paraphrased in George WashingtonÂ’s first state of the union address, as well as by Presidents Lincoln and Reagan. Margaret Thatcher (United Kingdom) and Stephen Harper (Canada) also believe in peace through strength.
Most wars start when a dictator or monarch (e.g. – Hitler) believes he can win a conflict against a weak neighbor quickly and easily. Perhaps to test out his plan, he takes some small aggressive steps to make sure that no one is going to stop his aggression (e.g. – rebuilding the Luftwaffe, occupying the Rhineland, annexing the Sudetenland, annexing Austria, invading Poland). Once he is able to confirm over and over that no democracies are going to stop his conquests by force, he attacks.
The way to stop most wars is to make dictators believe that you have the means and the will to stop their aggression. Clinton allowed about a half dozen attacks in the 90s without any reprisal, (e.g. – World Trade Center, USS Cole, etc.) We did not respond to these terrorist attacks on our national interests. As a result, Bin Laden would joke about how the USA was a “paper tiger” that did not have the stomach for war. He thought that a few American losses would make us pack up and go home.
Contrast ClintonÂ’s view with Ronald Reagan. ReaganÂ’s biography at the White House web site says this:
“In foreign policy, Reagan sought to achieve “peace through strength“. During his two terms he increased defense spending 35 percent, but sought to improve relations with the Soviet Union.