Chinese internet users called it a “proxy war”: three weeks ago, two pensioners in a Shanghai park got into a fight over the Ukraine conflict that left Russia backing Shen Jianguo, 70, bleeding from the ear and trending on social media.

China’s government has leaned towards Russia by backing Moscow’s complaints about Nato expansion and refusing to call its actions an invasion. But while Beijing’s censors are working hard to suppress any criticism of that position, the conflict has ignited heated controversy both among Chinese policy experts and the public.

Analysts say the debate shows the strains caused by a clash between alignment with Russia and long-avowed Chinese diplomatic principles as Beijing struggles to assess how the war will affect its interests.”The discussions are pretty intense. There are a lot of different points of view on this, the debate is extremely diverse,” said Zhao Tong, senior fellow at Carnegie Tsinghua Center in Beijing.

The fiercest arguments are raging about basic beliefs. “It is about right and wrong,” said Yun Sun, a China foreign policy expert at the Stimson Center in Washington. “I am struck by how intense the debate is, not just among policy folks, but also among ordinary people.”Zhang Guihong, an international relations professor at Fudan University, said China needed to better balance its values and its interests.

“We have been leaning towards Russia. But there is a bottom line which we need to insist upon,” he said, citing respect for sovereignty and territorial integrity, two principles China says guides its foreign policy.