Ree graduated in 1944 with a physics degree; he then went to Fengtian, Manchukuo (today Shenyang, Liaoning in the People's Republic of China) to work for an aircraft company.

After the surrender of Japan in 1945 and the end of Japanese rule in Korea, Ree returned to his home country and in 1947 took up a teaching position in the mathematics department at Seoul National University as an assistant professor.

[2] During the Korean War, he fled south to Busan, and in 1953 he was awarded a Canadian scholarship to allow him to study for a Ph.D. degree at the University of British Columbia in Vancouver, Canada.

Following the award of his doctorate, Ree was appointed as a lecturer at Montana State University, despite facing several problems regarding his labour permission and nationality.

[8][9] Ree refused the order, which caused him considerable difficulty, but in the end the Canadian government treated him as a de facto stateless person and granted him permanent residency in Canada.

Ree's family was divided by the Korean War, with his father, older sister, and other relatives having stayed in their hometown of Hamhung.

Ree requested help from Erdős, who as an internationally-famous Hungarian citizen faced fewer restrictions on travel or communication in either capitalist or communist countries.