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U.S. Defense Secretary Chuck Hagel (L), and Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey talk about the Defense Department's FY2014 budget request during a briefing at the Pentagon, April 10, 2013 in Arlington, Virginia. Hagel also spoke about the ongoing situation with North Korea. (Photo by Mark Wilson/Getty Images)

Since when has it been considered smart to tell your enemies what your plans are?

Yet there on the April 8 front page of the New York Times was a story about how unnamed "American officials" were planning a "proportional" response to any North Korean attack. This was spelled in an example: If the North Koreans "shell a South Korean island that had military installations," the South Koreans would retaliate with "a barrage of artillery of similar intensity."

What conceivable purpose can be served by telling the North Koreans in advance that they need fear nothing beyond a tit for tat? All that does is lower the prospective cost of aggression.

When the Japanese bombed Pearl Harbor, should we have gone over and bombed a harbor in Japan? Does anyone think that this response would have stopped Japanese aggression?

Before the clever new notion of "proportional" response became vogue, our response to Pearl Harbor was ultimately Hiroshima and Nagasaki. And Japan has not attacked or even threatened anybody since then. Nor has any war broken out anywhere that is at all comparable with World War II.

Which policy is better? There was a time when we followed the adage "By their fruits ye shall know them." The track record of massive retaliation easily beats that of the more sophisticated-sounding proportional response.

In ancient times, when Carthage attacked Rome, the Romans did not respond "proportionally." They wiped Carthage off the face of the Earth. That may have had something to do with centuries of what was called the Pax Romano -- the Roman peace.

When Argentina invaded the Falkland Islands in 1982, the British sent troops to take the islands back -- despite American efforts to dissuade Prime Minister Margaret Thatcher from doing that.

For more than a century since the British settled in the Falkland Islands, Argentina had not dared to invade them. Why?

Until recent times, an Argentine attack on a British settlement would be risking not only a British counterattack there, but the danger of a major British attack on Argentina. That could mean leaving Buenos Aires in ruins.

Today, Argentina's government is again making threatening noises about the Falkland Islands. Why not? The most the Argentines have to fear is a "proportional" response to aggression. When threats are rewarded, why not make threats, when there are few dangers to fear?

Can you think of any war prior to Iraq and Afghanistan where the United States announced to the world when it planned to pull its troops out? What has this accomplished? "By their fruits ye shall know them." What have been the fruits?

First of all, this talk in Washington about not only pulling out, but announcing in advance what their pullout timetable was, meant that Iraqi political leaders knew a powerful Iran was on their border permanently, while Washington was a long way away and intended to stay away.

Should we be surprised that the Iraqi government has increasingly come to pay more attention to what Iran wants than to what Washington wants? Once more, vast numbers of American lives have been sacrificed winning victories on the battlefield that the politicians in Washington then frittered away and turned into defeat politically.

There is no need to respond to a North Korean artillery barrage by wiping North Korea off the map. But there is also no need to reassure the North Koreans in advance that we won't.

What announcing the doctrine of "proportional" response does is lower the price of aggression. Why would we want to do that?

Thomas Sowell is a senior fellow at the Hoover Institution at Stanford.