The Korean War You Know
And the one SIGINT knows
When North Korean forces attacked on June 25th, 1950, it was a complete surprise to the South Korean government and military, their US advisors, the United Nations, and Gen. Douglas MacArthur.
When North Korean forces attacked, there were no American signals intelligence (SIGINT) assets in Korea, or even pointed at Korea. But I repeat myself.
Six weeks later, American, South Korean, and UN forces that had been rushed into the Pusan beachhead miraculously held off a massive armored envelopment by North Korean forces.
Six weeks later, the United States had spun up an entire Army Korean language signals intelligence operation with borrowed radio gear that produced timely and accurate information, allowing Gen. Walton Walker (see photo) to dispose his exhausted, battered, and under-armed units to win a narrow victory against overwhelming odds. But I repeat myself.
When North Korean forces attacked, they had significant air power that inflicted heavy losses to men, material, and morale. Six weeks later, the Royal Navy and US Navy had annihilated most of North Korea’s air fleet on the ground.
When North Korean forces attacked, the nascent US Air Force and US Navy rose to the occasion with a massive air lift and sea lift of soldiers, supplies, machines, and Marines to Pusan while SIGINT platforms began targeting the North Korean air fleet for annihilation. But I repeat myself.
The secret SIGINT history of the Korean War adds a whole new context to events. Doesn’t it?
For example, while reading Edwin Hoyt’s journalistic The Pusan Perimeter: Korea 1950, we learn that on 15 July, Gen. Earle Partridge, the US Air Force commander in the Far East, ordered strikes on the North Korean air park at Kimpo. “But then air intelligence learned that the major enemy airfields were Pyongyang and Yonpo, and orders were given to the carrier Valley Forge to take care of them,” he says.
Intelligence. What intelligence? Why, SIGINT, of course. Isn’t it obvious?
Perhaps not. Well, consider your average everyday pilot. Upon belting themselves into the seat, the pilot will do a radio check as part of their routine checklist. Airline pilots are in constant communication with the control tower throughout takeoff. Everyday operations at a busy airport make the surrounding ionosphere glow in the FM band like a light bulb, signalling: I’m right here! Look at me!
The rest is traffic analysis, which is easy to learn using note cards. A discerning team of people with minimal flight operations knowledge will soon be able to tell when all the North Korean planes are on the ground — the “bulb” is dim.
Elsewhere, Hoyt credits reconnaissance airplanes as Walker’s sole source of intelligence on North Korean movements in late July. As I have explained before, air recon generally looks in places where other intelligence has first suggested that they should see what is going on. To use a term that Hoyt would have understood, aerial photos or scout reports are usually the corroborating sources to information gleaned by SIGINT.
As American resistance stiffened on the Nakdong River, Hoyt notes, Kim Il-sung “was now becoming obdurate about the slowdown in the rush for Taegu.” Hoyt knows this because nameless sources in Washington told him.
What those sources did not say is that they knew about North Korea’s command and control tirades because someone was listening, recording, and transcribing them.
Rallying his troops on 29 July 1950, Gen. Walker made it clear that he would stand at Pusan. “We are fighting a battle against time,” he said, knowing that reinforcements were streaming in by the hour.
There will be no more retreating, withdrawal or readjustment of the lines or any other term you choose. There is no line behind us to which we can retreat. There will be no Dunkirk, there will be no Bataan. A retreat to Pusan would be one of the greatest butcheries in history. We must fight until the end. We will fight as a team. If some of us must die, we will die fighting together. I want everybody to understand we are going to hold this line. We are going to win.
It was a line shaped by SIGINT. There is the Korean War that everyone knows, and then there is the secret war, the one where rapid response by American signals intelligence turned the tide of battle —and got no credit at all for half a century. Even though the truth has been declassified for more than two decades now, documentaries and books are still leaving out this context. It is time to rectify that travesty.