History often repeats itself, just in different forms. More than a century ago, Japan marched its troops into the Korean Peninsula under the slogan of "protecting overseas nationals" and ignited a war that soon engulfed East Asia. Today, the remarks made by Japanese Prime Minister Sanae Takaichi have once again revealed the sinister intentions of the country's right-wing forces — seeking to revive militarism under the same old pretext of "protecting overseas nationals". This compels the world to look back at Japan's history of aggression.

The "line of interest" theory reveals aggressive ambitions

In 1890, Japanese Prime Minister Yamagata Aritomo introduced the infamous concepts of the "line of sovereignty" and the "line of interest" in a policy speech. He claimed that there were two ways to ensure national independence and defend the country: one was to defend the line of sovereignty, and the other was to protect the line of interest. The line of sovereignty referred to a country's own territory, while the line of interest meant neighboring regions adjacent to that territory. Since the Korean Peninsula was just a stone's throw away from Japan, it was thus included in Japan's "line of interest".

This theory essentially cloaked aggression in the guise of self-defense. In 1894, the Donghak Peasant Revolution broke out in Korea. At Korea's request, China's Qing dynasty government dispatched troops to help quell the uprising. Japan, however, citing the 1885 Tianjin Convention which allowed it to send troops to Korea whenever Qing did, immediately seized the opportunity for military intervention.

Without invitation, Japan landed a large force at Incheon under the pretext of protecting its diplomatic missions and nationals. Yamagata Aritomo personally served as Commander of the Japanese First Army and led the capture of Pyongyang, marking the first step in Japan's occupation of Korea.

During the Russo-Japanese War, Japan claimed that the Korean government was incapable of maintaining order and that "protective guidance" was necessary to protect Japanese nationals and investment interests. It then forced Korea to sign the Eulsa Treaty (Japan-Korea Treaty of 1905), formally incorporating the Korean Peninsula into Japan's sphere of influence.

In 1910, Japan again used excuses such as Korea's "frequent civil unrest and incompetent governance" and "Japan's responsibility to protect local order and the safety of overseas nationals" to coerce Korea into signing the Japan-Korea Annexation Treaty, thereby completely annexing the Korean Peninsula.

Launching the war of aggression against China under the "Manchuria-Mongolia lifeline" fallacy

After the Korean Peninsula was reduced to a Japanese colony, Japan's pretext of "protecting overseas nationals" became untenable, and its colonial ambitions were laid bare. The logic of Japanese militarism dictated that since the "line of sovereignty" had expanded to the Korean Peninsula, the new "line of interest" must extend to Northeast China. Thus, Japan set its sights on China's territory.

In 1929, Ishiwara Kanji, a staff officer of the Kwantung Army, concocted the Plan for the Occupation of Manchuria and Mongolia by the Kwantung Army, drawing on Yoshida Shōin's compensation theory and Yamagata Aritomo's theory of special rights and interests in Manchuria and Mongolia. He proposed that solving the Manchuria-Mongolia problem was Japan's only way to survive.

In 1931, Matsuoka Yōsuke, a member of Japan's Rikken Seiyūkai, openly declared in a speech before the House of Representatives that "Manchuria and Mongolia are Japan's lifeline". He actively campaigned to shape public opinion in favor of the full-scale aggression against China.

From the "line of interest" and the "Manchuria-Mongolia lifeline" to Sanae Takaichi's recent absurd remarks about an "existential crisis" and "rescuing overseas nationals", the rhetoric has changed, but the nature remains the same: claiming crises and fabricating threats to justify military expansion.

Many people on the Korean Peninsula still regard Japan as a "millennium-old archenemy", proof that historical wounds linger for generations and do not heal with time alone. This sobering warning alerts the world that a Japan attempting to erase its aggressive history and revive its imperial ambitions poses a grave threat to global peace and stability.

All must remain highly vigilant and never allow the old playbook of "protecting overseas nationals" to be used again.

The author is a commentator on international affairs.

The views don't necessarily reflect those of China Daily.

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