China and Japan keep running into bumps in their relationship, with tensions over political and economic issues stemming from their complicated history.

The beginning of the new year did nothing but heighten mounting tension, as China expanded its export control powers over items it believes have dual use in the military, rejecting a petition from the Japanese Foreign Ministry. Wu Jianghao, China’s ambassador to Japan, publicly supported the move, calling it “entirely legitimate, reasonable and lawful.”

The ban may include rare-earth materials, which are crucial to modern technology. Japanese Industry and Trade Minister Ryosei Akazawa didn’t confirm it, but said that the ban and China’s grasp of “the export controls have already affected our country tremendously.”

Japan’s government announced that it will closely monitor how its agricultural, fisheries, and other exports are handled in China, following delays at customs. In particular, sake exports have been blocked at Chinese customs for months, partly as a symbolic gesture aimed at one of Japan’s most well-known products. Japan’s chief cabinet secretary, Minoru Kihara, told reporters that “we will closely watch the situation and take appropriate measures,“ without elaborating further on what those measures may be.

China has been ramping up its posturing against Japan since the appointment of a new conservative prime minister, Sanae Takaichi. Her government is considering raising the country’s military, and she said that she wouldn’t rule out intervention against China over Taiwan. This irked Beijing, which considers Taiwan a runaway region of China and has always had friction with Tokyo over military matters. Japan brutally occupied China in the years before and during World War II, and has always maintained an ambivalent stance about condemning atrocities committed by its army during those years.

China’s People’s Daily published a rather harsh editorial on Friday that used historical background to condemn the current Japanese leadership, saying that “history serves as a stark warning, yet the Japanese right wing is repeating its old tricks.“ The piece appealed to “peace-loving Japanese people“ to stand up and “remain vigilant“ against the right-wing militaristic strategy.

This article used information from The Associated Press.