Two giant pandas at a Tokyo zoo will be returned to China in January, Japanese media reported Monday, a move that could leave Japan without the popular animals for the first time in about 50 years.

The black-and-white bears were loaned to Japan under China’s so-called “panda diplomacy” program and have long been seen as symbols of friendship between Beijing and Tokyo since the two countries normalized diplomatic ties in 1972.

Japan currently has only two pandas — Lei Lei and Xiao Xiao — at Ueno Zoo in central Tokyo. The twins are expected to be sent back to China about a month before their loan period expires in February, according to the Asahi Shimbun and other Japanese media outlets.

Tokyo’s metropolitan government had sought to keep the immensely popular pandas, which draw large crowds to the zoo, but China did not agree, the Nikkei business daily reported. The Tokyo Metropolitan Government declined to comment when contacted by AFP.

Asahi also reported that Tokyo is separately seeking to borrow a new pair of pandas, though their arrival before Lei Lei and Xiao Xiao are returned is considered unlikely.

Relations between Asia’s two largest economies have recently worsened after Japan’s new conservative prime minister, Sanae Takaichi, suggested Tokyo could intervene militarily if Taiwan were attacked. The remarks angered Beijing, which considers the self-governed island part of its territory.

Ueno Zoo has long been a beneficiary of panda diplomacy and has cooperated with institutions in China and the United States to breed giant pandas. Lei Lei and Xiao Xiao were born in 2021 to their mother, Shin Shin, who arrived in Japan in 2011 and was returned to China last year.

Breeding pandas in captivity is notoriously difficult because of challenges that include trouble mating, false pregnancies and high mortality rates among newborn cubs.