China only has one formal treaty ally – North Korea. However, next week, President Xi Jinping of China will pay a state visit to the North’s bitter rival – South Korea. The Chinese president’s arrival in Seoul will be regarded as a grave affront by the North Korean government, particularly since Mr Xi has yet to visit Pyongyang.

However, a warmer relationship between China and South Korea is a rare hopeful sign that the situation on the Korean peninsula may be amenable to improvement. Given that the Korean conflict is one of the most dangerous and intractable in the world that is welcome news.

It has long been clear that only China has the leverage to exert pressure on North Korea. The regime there, led by Kim Jong Un, is almost entirely dependent on China for trade, aid and energy. Yet there are growing signs that President Xi and the Chinese government regard the North Koreans as a danger and an embarrassment. North Korea’s third nuclear test in February 2013 seems to have received a frosty reception in Beijing. The recent purge of Kim Jong Un’s uncle, who was said to have been close to the Chinese, has not improved matters.