Hundreds of South Korean activists gathered on Saturday in Seoul, South Korea, in public protest following reports earlier this week that Japan will begin releasing radioactive water into the Pacific Ocean.

According to Japanese newspaper Asahi Shimbun, Japan will begin their operation to release “contaminated” radioactive water which has been stored in the region since the Fukushima nuclear power plant suffered from a devastating tsunami in 2011. The plan has been approved by Japan’s nuclear regulator, as well as the International Atomic Energy Agency. However, The Pacific Island Forum earlier this year expressed concerns regarding long-term ramifications for the environment and public health, as well as setting a precedent for other nations disposing of nuclear waste.

The demonstration, organized by activist group Korea Radiation Watch, is reflective of the mixed responses that this plan has received internationally. WION reports that one organizer, Choi Kyoungsook, explained:

If it is discarded, radioactive substances contained in the contaminated water will eventually destroy the marine ecosystem […] We are opposed […] because we believe the sea is not just for the Japanese government, but for all of us and for mankind.

Japanese officials argued that the water, which has been treated to remove most radioactive elements, excluding tritium, will be diluted by seawater, bringing it within approved levels.

The Guardian reports that the 1.3 million tonnes of water will be released via an undersea shoreline tunnel, in a process which is expected to take over 30-40 years to complete.

President Joe Biden is scheduled for an upcoming summit with Japanese Prime Minister Fumio Kishida and South Korean President Yoon Suk Yeol on August 18.