This goes back to the rise and fall of super powers in the world. At the time the UK was still the world super power but the USSR, Nazi Germany, US, and Japan where all rising super powers.

In a sence there was some growing concern about the growing powers in the UK but it was not until the mid 30s that the US out pased the UK in GDP. Japan however was very much relient on oil imports much like how China is now on raw goods.

The European powers where more concerned however of the growing power of the USSR.