Here is a tricky international dilemma. What does a country do when it has two powerful friends with whom it wants — and needs — to have ever closer and better relations, but when unfortunately the two countries concerned dislike and even fear each other intensely?

This is precisely the United Kingdom's position in the case of China and Japan. As the U.K. looks outside Europe to expand new markets, and new sources of investment, following the Brexit decision to leave the European Union, it becomes increasingly important to be on excellent terms with both these key Asian and global powers with their colossal consumer markets.

But for the U.K. this means maintaining a delicate and skilled balance to avoid accusations of unduly favoring one source or the other, or letting down friends or similar complaints.