The four decades between 1905 and 1945, starting when Korea was forced to sign the Eulsa Treaty, which made it a protectorate of Japan, is largely considered a lost period in the history of the country’s foreign policy.

As a result of the 1905 treaty -- which laid the foundation for the country’s subsequent annexation in 1910 -- Korea was stripped of its diplomatic sovereignty, losing its voice and representation on the international stage until its liberation in 1945.

With Japan’s voice replacing Korea’s during those decades, some may wonder whether Korea’s foreign policy under Japan’s colonial rule could be considered a valid subject for academic research in international relations. And if so, what would it mean? These are some of the questions Ku Dae-yeol, professor emeritus at Ewha Womans University, has pondered for decades.

“Korea 1905-1945: From Japanese Colonialism to Liberation and Independence,” published in April by Renaissance Books, is the product of Ku’s lifelong study of this subject. It delves into Japan’s colonial rule of Korea and what it meant for Korea’s foreign relations, a topic that has largely been neglected by scholars of Korean foreign affairs.

“Strictly speaking, international relations do not exist without a nation-state, which is the main actor,” Ku told The Korea Herald in a recent interview. “But we also have to consider the fact that Korean people have lived for centuries on the peninsula and continued to live during this period, and in the perspective of international politics, the strategic and geopolitical value of the peninsula and the residents still remain valid.”

Moreover, he emphasized that previous studies on Korea’s colonial era were mostly based on how the Western powers viewed South Korea. Most of the time the Korean issue was regarded as one of the “problems of the colonies” -- it was put on the back burner and only dealt with as part of the wider area of East Asian affairs.

“In order to get a true picture of Korea during this time, it is important to consider both international perspectives and bilateral relations between Japan and Korea,” he said. “Getting a full scope of perspectives is important, because there are areas that need to be reevaluated and modified from prejudice and skewed interpretations.”

Understanding the Korean independence movement is also critical, he stressed, as it at times represented the voice of Korea and its bid for independence on the international stage.

The book, at 496 pages, weaves together vast archival records from Korean, Japanese, Chinese, American and British sources during this period, particularly showing how British and American state officials viewed Korea under Japanese rule.

The book is divided into two parts -- the first part detailing the period of annexation up until the 1930s, and the second part in the 1940s. It also covers how the policies of the US, China, the UK and the Soviet Union toward Korea changed and what role those countries played in the liberation, as well as in the subsequent division of the two Koreas.

“What is unusual about Korean diplomatic history is the extraordinary extent to which outside powers shaped Korea’s domestic political landscape,” Ku wrote in the book. For this reason, he believes a thorough examination of the outside powers’ perceptions and reactions toward Korea is critical in understanding today’s diplomatic challenges.