President Moon Jae-in came forward Wednesday to add weight to Seoul’s response to a controversial decision made by Tokyo a day earlier to discharge contaminated wastewater from a crippled nuclear power plant into the Pacific Ocean.

While meeting with Japan’s new ambassador here, Koichi Aiboshi, to receive his credentials, Moon said there is great concern among South Koreans, as the two nations are geographically close to each other and have shared waters. He asked the envoy to convey his message to Tokyo.

Moon later instructed his government to “proactively consider” bringing the matter to the International Tribunal for the Law of the Sea.

But the concerns raised by Moon and other South Korean officials appear to be falling on deaf ears in Tokyo.

On Tuesday, the Japanese government announced a plan to release what it calls “treated water” from the Fukushima Dai-ichi Nuclear Power Plant into the ocean. An estimated 1.25 million tons of such water are in temporary storage at the nuclear power station on the northeastern coast of Japan, which was devastated by a tsunami triggered by an earthquake in March 2011.

Japan plans to start discharging the radioactive water into the sea in 2023 in what is set to be a decadeslong process, as all storage tanks at the Fukushima plant are expected to be full by the end of 2022. It says the contaminated water will be released after being diluted to a level that is harmless.

Tokyo has been successful in securing understanding from the US and the International Atomic Energy Agency with regard to the disposal plan. The US State Department noted that Japan has been transparent about its decision on the water release and appears to have adopted an approach in accordance with globally accepted nuclear safety standards. Experts at the international nuclear watchdog also made a similar assessment.

This might embolden Tokyo to ignore concerns from South Korea and other neighboring countries.

But the lack of prior consultations with its immediate neighbors is duly heightening concerns about the proper monitoring of the water disposal.

It may be that sufficiently diluted radioactive water would not bring damage in a direct manner. But it is still uncertain what long-term effects the planned release of an unprecedented amount of contaminated water will have on the marine ecosystem and people in neighboring countries.

Japan could have further delayed the water release by building additional storage facilities outside of the Fukushima plant after gaining consent from nearby residents. With the half-life of tritium at 12.3 years, most of the radioactive material will have disappeared in storage tanks in about three decades, making it far safer to dump into the ocean.

Cheong Wa Dae officials say the office of the presidential secretary for legal affairs has begun a review of various options with regard to the possibility of taking Japan’s move to the international court. From a realistic and technical viewpoint, however, it seems difficult for Seoul to make its case at the tribunal, as it would have to prove direct damage from Tokyo’s move, which the US and the IAEA see as meeting global safety standards.

Instead of insisting on its objection to the discharge of the contaminated water, Seoul needs to focus on ensuring an objective verification of the safety of the measure through thorough monitoring. It will be essential for South Korea to be included in the monitoring mission to be formed by the international nuclear watchdog after Tokyo begins releasing radioactive water from the Fukushima plant.

The discord between South Korea and Japan over the contaminated water disposal runs the risk of hampering efforts to enhance not only the strained bilateral relationship but also their trilateral cooperation with the US.

It is apparently no coincidence that Tokyo announced the plan for the radioactive water release a few days before Japanese Prime Minister Yoshihide Suga is to hold his first in-person meeting with US President Joe Biden in Washington. Shortly after the announcement was made, Seoul delivered its concerns over Tokyo’s decision to the US, according to South Korea’s Foreign Ministry.

Despite its positive response to Japan’s move, the Biden administration needs to pay more serious attention to Seoul’s call on Tokyo to ensure the transparent disclosure and verification of information related to the process of treating the contaminated water.