China’s leader raised the ancient Greek historian Thucydides when he met the US president in Beijing

Trump-Xi China summit – follow live

A messy war in the Middle East. Tensions in Taiwan. When the leaders of the world’s two superpowers met in Beijing this week, these were the flashpoints everyone expected they would talk about.

Instead, Chinese leader Xi Jinping threw another, ancient war, into the mix.

In his opening remarks on Thursday, Xi made reference to the Peloponnesian War in ancient Greece, a decades long conflict that erupted between Athens and Sparta in 431BC.