Japan's strong border was the first unequal treaty signed by the North Korean government.

In January 1876, in the name of holding accountable for the "Yunyang" incident, the Japanese government sent Kiyotaka Kurori as its plenipotentiary, leading 7 warships and more than 1000 marines to North Korea, and arbitrarily demanded that the North Korean government immediately send a plenipotentiary to negotiate the conclusion of a treaty. Under the threat of force, the North Korean government signed the so-called "Treaty of Japan-Japan Resumption"(the "Treaty of Ganghua") on Ganghwa Island on February 26.

The main contents are: in addition to Busan, North Korea has opened two ports, Incheon and Wonsan; Japan has free trade; Japan has established an embassy in Seoul and dispatched consuls to various ports; crimes committed by Japanese in North Korea should be handled by Japanese consuls. The "Jianghua Treaty" seriously undermined the sovereignty of the North Korean government, and North Korea began to become a semi-colony of Japan.