Crossing the Korean Rubicon

Stopping Iran - Norman Podhoretz, WSJ, 23rd Jan 2008

The CIA was established in 1947 in large measure to avoid another surprise attack like the one the U.S. had suffered on December 7, 1941 at Pearl Harbor. But only three years after its founding, the fledgling agency missed the outbreak of the Korean war. It then failed to understand that the Chinese would come to the aid of the North Koreans if American forces crossed the Yalu river.

If American forces had crossed the Yalu then the Chinese would have been perfectly justified to react to an invasion of their country as this river lies on the Chinese Korean border.

Later in the war the USAF would take pains to stay on the Korean side of the river while bombing the bridges over it used by the Chinese to resupply their forces.