Xi Jinping rarely raises his voice in meetings - Chinese leaders spend their entire diplomatic careers building exactly that kind of controlled verbal posture. So when he did it at the recent meeting with Donald Trump in Beijing, that means something. The topic he pulled out of diplomatic calm: Japan.

According to the Financial Times' reporting, this was the tensest moment of the two-day summit. Xi criticized what he calls the "remilitarization" of Japan, and the policies of Prime Minister Sanae Takaichi. American representatives were caught off guard - Japan was not a planned point on the agenda.

Trump responded with a generic line - that Japan has to bolster its security because of threats from North Korea - without tying Japanese military build-up to Chinese interests. But for Beijing, the problem is bigger: Takaichi recently suggested that Chinese actions against Taiwan could threaten Japan's very survival. That's a sentence Beijing remembers.

The context is wider. The Asian security triangle - Taiwan, North Korea, China - is being redefined. Japan sits in the middle, raising defense spending and deepening ties with the US. Analysts argue that Chinese pressure may be counterproductive - giving Tokyo even stronger justifications for regional security partnerships.

When Xi raises his voice, the Balkans should pay attention. Not because it concerns us right now - but because when the two largest economies clash over a third country, the fallout for global markets, supply chains and energy costs reaches every economy, ours included.