More than one million metric tons of treated radioactive water will soon be released from the destroyed Fukushima nuclear plant into the ocean, following a decision by the Japanese government. The plan has raised strong criticism at home, especially by fishermen, and among neighboring countries such as China.

The decision comes more than a decade after the nuclear disaster in 2011 at the Fukushima Daiichi plant, which suffered meltdowns in three of its reactors due to an earthquake and a tsunami. Seeking to control the radioactive fallout, over 1,000 tanks were used to hold the treated but still radioactive water that kept the reactors cool.

But the solution was only temporary, as the company in charge of the plant is now running out of storage room for this water. Experts have repeatedly suggested releasing it into the sea in a controlled manner, but locals vehemently opposed the plan. Now, the government said releasing the water was the “most realistic option.”

Prime minister, Yoshihide Suga, told a meeting of ministers this week that the government had decided that releasing the water into the Pacific Ocean was “unavoidable in order to achieve Fukushima’s recovery”. Work to release the water will begin in about two years, with the entire process expected to take decades.

The water stored in the tanks won’t be discharged as it is. Instead, it will be treated through a system that removes most of the radioactive material except for tritium, an isotope of hydrogen not harmful to humans in small amounts. Tritium “emits weak radiation” and its impact on health “is very low,” a government statement reads.

The discharging process will be monitored by third parties, including the International Atomic Energy Agency (IAEA). The agency’s head Mariano Grossi told CNN there is “no harm” in releasing treated water into the sea. This has been done in many parts of the world and no adverse environmental impact was reported, Grossi explained.

Still, the reassurances of Japan haven’t settled the nerves of neighboring countries, environmental groups, and local fishermen — worried over the implications of Japan’s decision. China said the plan was “extremely irresponsible”, and accused Japan of disregarding “domestic and foreign doubts and opposition”. In a statement, the Chinese foreign ministry said the releasing the water will “seriously damage international public health and safety and the vital interests of the people of neighboring countries.”

South Korea shared the concern, saying the decision could “directly or indirectly affect the safety of the Korean people and the surrounding environment in the future.” The country’s Foreign Affairs Ministry spokesman Choi Young-sam said at a news briefing that Japan should have consulted with neighboring countries and be more transparent.

Meanwhile, fishing communities said the water’s release will undo years of hard work to rebuild consumer confidence in their seafood. Kanji Tachiya, who heads a local fisheries cooperative in Fukushima, express his disagreement to AFP: “We can’t back this move to break that promise and release the water into the sea unilaterally.”