On 21 June, Kim Il-Sung revised his war plan to involve a general attack across the 38th Parallel, rather than a limited operation in the Ongjin Peninsula. Kim was concerned that South Korean agents had learned about the plans and that South Korean forces were strengthening their defenses. Stalin agreed to this change of plan.
Competitions resumed with the 1950 World Cup in Brazil, which was the first to include British participants. British teams withdrew from FIFA in 1920, partly out of unwillingness to play against the countries they had been at war with, and partly as a protest against a foreign influence to football, but rejoined in 1946 following FIFA's invitation. England's involvement, however, was not to be a success.
The conflict escalated into warfare when North Korean military (KPA) forces—supported by the Soviet Union and China—crossed the border and advanced into South Korea on 25 June 1950.
On 26 June 1950, the National Assembly supported a crucial bill written by Milovan Đilas and Tito regarding "self-management", a type of cooperative independent socialist experiment that introduced profit sharing and workplace democracy in previously state-run enterprises, which then became the direct social ownership of the employees.
In June 1950, Suzy Delair performed rehearsals of the song "C'est si bon" with Aimé Barelli and his Orchestra at the Monte Carlo casino where Louis Armstrong was finishing the evening. Armstrong enjoyed the song and he recorded the American version in New York City on June 26, 1950.
On June 27, 1950, after the outbreak of fighting in Korea, Truman ordered the U.S. Navy's Seventh Fleet into the Taiwan Strait to prevent further conflict between the communist government on the China mainland and the Republic of China (ROC) on Taiwan.