Japan may take World Trade Organization action against China, which banned all Japanese seafood imports in response to Tokyo’s release of treated wastewater from the wrecked Fukushima nuclear plant into the ocean.

Japanese Foreign Minister Yoshimasa Hayashi said Tuesday the country will take any necessary action at the WTO or other frameworks over China’s move. He also confirmed that a brick was hurled at the Japanese embassy in Beijing, adding to reports of harassment faced by Japanese people and businesses in China.

The Chinese government has staunchly opposed Tokyo’s plan to discharge treated water from the ruined Fukushima nuclear plant even though Japan says it’s safe — a view backed by the International Atomic Energy Agency. Japan started the release last Thursday, sparking retaliation from Chinese authorities.

There’s also been anger and calls for boycotts of Japanese products on Chinese social media. The embassy and schools across China have experienced some sort of harassment, according to a Japanese government official who declined to be named discussing the sensitive issue. 

People threw eggs at the embassy building in Beijing, the official said. Others held impromptu protests outside. The mission received several nuisance calls, and received an anonymous delivery of two baskets of chrysanthemums, according to the official. The flowers in Japan are associated with funerals. 

Schools attended by Japanese children were also targeted. A passerby threw stones at a school in Qingdao, while in Shanghai, a man urinated at the front gate of a Japanese school, the official said.

Hayashi echoed calls from Prime Minister Fumio Kishida to China to take action to calm the situation. 

When asked about the brick incident during a regular press briefing Tuesday, Chinese Foreign Ministry spokesman Wang Wenbin said Beijing has ensured the safety and lawful rights of foreign nationals.