What factors made Korea vulnerable and appealing for military occupation? What geopolitical factors in the 20th century led Korea’s invasion and occupation in June 1950?

Korea was vulnerable and appealing for military occupation due to the lack of equipment and preparation the South had prior to the invasion.  The obvious appealing reasons are the simple fact that South Korea is at the tip of the peninsula and also had natural resources.  South Korea was also vulnerable due to the known hesitation the US would have getting involved in another war of attrition.  North Korea knew that they had the overpowering equipment and also the home field advantage.  The geopolitical factors that led to the invasion and occupation in June of 1950 were those of failed attempts to unify the peninsula and the USSR backing the North Koreans.  After World War II, the US backed South Korea as the USSR backed the North.  The tensions between these to countries would ultimately lead to the breakdown of any attempts to unify the peninsula under one government.