Source: October 1950 – Wikipedia
On October 15, 1950 (one day after the Chinese army had crossed the Yalu) U.S. President Harry S. Truman and General Douglas MacArthur met on Wake Island to confer about the progress of the Korean War.
Truman and MacArthur met privately at the conference and, therefore, there is no record of their conversation. However, by most reports, MacArthur assured Truman that Communist China would not send troops into Korea, and if they did, he would would destroy them.
In his fascinating book Douglas MacArthur: American Warrior, Arthur Herman describes the Wake Island meeting:
“What are the chances of Chinese or Soviet interference?” Truman asked.
“Very little,” MacArthur replied, puffing on his pipe…”Had they interfered in the first or second months it would have been decisive. We are no longer fearful of their intervention.”