Answer:
In order to stop Germany.
Explanation:
The United States and Britain create joint operations in response to Germany's Lebensraum because for Lebensraum Germany declared war and attacked on the European countries so in order to stop Germany from expanding, a joint operation must be conducted by United States and Britain . That time Germany is very powerful so alone operation by Britain or United States was not profitable. Due to brutal behaviour of Japan, Secretary of War Harry Stimson shift its focus to Japan. Bombing of Japan on pearl harbor where US ships are standing, nuclear bomb attack was held on Japan.
