We're a bit late in deciding as the Korean War would've started on 25 June 1950. It's October at the time of this post.
Now the events preceding the war are as follows: (I.E. Background)
Korea was a part of the Japanese Empire, following WWII, since there was no currently formed government to give the Korean Penisula to like in China (China was given to the Republic of China which was still a thing unlike the Korean Government in which there was none).
So the UN splits Korea in between USSR and USA. Forming respective governments in hopes they'll eventually unite. Except not because USSR made a communist government and U.S. made a capitalist one. You can understand why they did not unite.
(Important or Deciding Factors have been bolded)
Kim began seeking Stalin's support for an invasion in March 1949, travelling to Moscow to attempt to persuade Stalin. Initially, Stalin did not think the time was right for a war in Korea. Chinese Communist forces were still fighting in China. American forces were still stationed in South Korea (they would complete their withdrawal in June 1949) and Stalin did not want the Soviet Union to become embroiled in a war with the United States.
By spring 1950, Stalin believed the strategic situation had changed. The Soviets had detonated their first nuclear bomb in September 1949; American soldiers had fully withdrawn from Korea; the Americans had not intervened to stop the communist victory in China, and Stalin calculated that the Americans would be even less willing to fight in Korea—which had seemingly much less strategic significance. The Soviets had also cracked the codes used by the US to communicate with the US embassy in Moscow, and reading these dispatches convinced Stalin that Korea did not have the importance to the US that would warrant a nuclear confrontation. Stalin began a more aggressive strategy in Asia based on these developments, including promising economic and military aid to China through the Sino-Soviet Friendship, Alliance, and Mutual Assistance Treaty.
Throughout 1949 and 1950 the Soviets continued to arm North Korea. After the Communist victory in the Chinese Civil War, ethnic Korean units in the Chinese People's Liberation Army (PLA) were released to North Korea. The combat veterans from China, the tanks, artillery and aircraft supplied by the Soviets, and rigorous training increased North Korea's military superiority over the South, which had been armed by the American military.
In April 1950, Stalin gave Kim permission to invade the South under the condition that Mao would agree to send reinforcements if they became needed. Stalin made it clear that Soviet forces would not openly engage in combat, to avoid a direct war with the Americans. Kim met with Mao in May 1950. Mao was concerned that the Americans would intervene but agreed to support the North Korean invasion. China desperately needed the economic and military aid promised by the Soviets. At that time, the Chinese were in the process of demobilising half of the PLA's 5.6 million soldiers. However, Mao sent more ethnic Korean PLA veterans to Korea and promised to move an army closer to the Korean border. Once Mao's commitment was secured, preparations for war accelerated.
"Chinese Communist forces were still fighting in China" "the Americans had not intervened to stop the communist victory in China"
Fighting is still continuing with PearTime (US) sending support to the RoC (Taiwan-based China).
"Stalin calculated that the Americans would be even less willing to fight in Korea"
Speculating here but, Since U.S. did support RoC, Stalin may have re-determined the US would be willing to fight in Korea, as once the situation gotten out of control in South Korea, the new Communist Korea could attack the US in RoC, making for a guarantee that U.S. must dedicate most of its force to Asia, assuming a war starts up.
"After the Communist victory in the Chinese Civil War"
With the US now supporting fighting element is renewed having the situation prior a stalemate on both sides until either recuperated and made a bold attack against the other.
"under the condition that Mao would agree to send reinforcements if they became needed" This bit is more speculation, but with a US presence threatening Mao, supposedly he would not agree as he still needs to end the Civil war.
"Mao was concerned that the Americans would intervene but agreed to support the North Korean invasion"
Speculation, with Mao's concerns now being fulfilled, perhaps he would not agree? Though it was stated that Mao desperately needed the supplies. Perhaps USSR would give them the support anyways because of the US presence?
What do you think? What should we do?
Korean War, Did it happen?