New IHO mapping standard drops 'Sea of Japan' label, Seoul says

A new international maritime mapping standard adopted in Monaco last week effectively removes the "Sea of Japan" label by replacing geographic names with numerical codes, South Korea said, calling the shift a milestone in a naming dispute nearly a century in the making.

The adoption resolves, in an unexpected way, Korea's decades-long push to place "East Sea" alongside "Sea of Japan" in international cartography — a dispute rooted in Korea's exclusion from the original 1929 standard while under Japanese colonial rule.

The International Hydrographic Organization formally adopted the S-130 standard at its fourth Assembly, held April 19-23 in Monaco, the Korea Times reported. The standard replaces S-23 — the organization's benchmark for defining the limits of oceans and seas — which had been in place since 1929.

Under S-130, each maritime area receives a unique numerical identifier derived from the latitude and longitude of its central point. The system eliminates geographic names — including "Sea of Japan" — from electronic navigation and geographic information systems, according to the Korea Times.

The outcome differs from what South Korea had long sought. Since 1997, Seoul has lobbied the international community to use "East Sea" concurrently alongside "Sea of Japan" in official cartography. Bilateral negotiations between Seoul and Tokyo repeatedly failed to produce a compromise on the naming dispute, the Korea Times reported.

The historical stakes behind the dispute are significant. When the original S-23 standard was adopted in 1929, Korea was under Japanese colonial control and was excluded from the deliberations that designated the maritime area between the Korean peninsula and the Japanese archipelago as the "Sea of Japan."

The S-130 framework is still in its early stages, with further technical refinement expected before full-scale implementation in electronic navigation and geographic information systems, according to the Korea Times.

The IHO Assembly first moved to develop S-130 as a successor to S-23 at its second session in 2020.