In spite of my career changes, historical study remains one of my significant interests.
From 2017, the Singaporean syllabus (new code 9752 – Higher 2) undergoes some revision but the topic on Korean War (1950-53) stays put.
For those who are seeking a rather brief overview, the British Broadcasting Corporation usually has many useful pieces. But I recommend the one from George Washington University through the Eleanor Roosevelt Papers Project. You also can find material from the US State Department on policy recommendation NSC-68.
Finally, one can consider the historical debate on the matter with two reviews by historian William Stueck – one from the Washington Post on Bruce Cumings (another historian) in 2010; and another in 2012 of Shen Zhihua’s translated work on primary documents relating to the Chinese, Soviets and North Koreans on E-International Relations (another useful site!)
Finally, one might need to look at the Chinese perspective as well…
Hope this post presents an adequate starting point for further inquiry!