For centuries, Japan's policy of seclusion (sakoku) saw it concentrate on coastal defences in order to repel foreign vessels. However, with the advances other maritime nations were making, it eventually became obvious that no longer would Japan be able to ignore the rest of the world. As an island power, it needed a modern navy. Turning to Britain for assistance, Japan quickly created a powerful modern fleet. It was this capable and confident navy that came out to fight the American Pacific Fleet.