No Trump! the rally of hundreds shouted, growing louder as it neared the United States embassy in the centre of South Korea's capital Seoul.

A line of police buses stopped them reaching the gates, but a stage and loudspeaker ensured their voices would soar above Gwanghwamun Square and within earshot of US President Donald Trump's representatives.

This was a small rally by the standards of South Korea's vibrant protest culture. And it was not the only one under way. A few hundred metres to the north, at the gates of Gyeongbokgung palace, marchers held aloft more banners as they chanted a very different message.

No China, along with a smattering of CCP [Chinese Communist Party] out!. Again, the numbers—several hundred people—were not huge for South Korea.

Nevertheless, this footfall through central Seoul on a sunny Saturday is an indication of the diplomatic dance South Korea's President Lee Jae Myung will have to perform this week as he hosts the leaders of both the US and China.

Seoul is—a key US ally. A friendship forged in blood, during the Korean War from 1950 to 1953, when American troops helped repel the North Korean invasion. The South still needs Washington's protection, but it also needs China, its biggest trading partner and a vital market for exports.

At 61, Lee is a seasoned politician, but he has his work cut out for him. His emphatic victory in June followed six months of turmoil. His predecessor Yoon Suk Yeol's short-lived martial law order triggered huge protests and a constitutional crisis that eventually led to his impeachment but left the country polarized.

Discontent towards Trump's politics has flared, with protesters highlighting grievances towards both the US and China's increasing dominance in Korean affairs. As President Lee navigates this complex landscape, he faces the challenge of appeasing both nations for South Korea's security and economic needs while addressing the voices of his citizens, who are feeling caught in the crossfire.