The British government's decision to join the new Asia Infrastructure Investment Bank (AIIB) proposed by China has opened the door to other governments that wish to act likewise. The result has been a rush to join the new financial institution as founding members, prompting a public and embarrassing rift with the United States.

There are many reasons for the sudden change of heart by European governments, but a key motivation is the fear of being left behind in the race to exploit economic opportunities with China. At the same time, however, Washington has been wrong-footed by the sudden change in policy and appears weakened and feckless as a result.

Britain announced last week that it was prepared to join the AIIB as a founding member, making it the first Western country to sign up to the $50 billion financial institution that aims to fill an infrastructure investment shortfall that threatens to limit Asia's growth prospects. Days after London signed up, the governments of France, Germany and Italy also said they would become founding members of the bank.