（初めに右欄で英語を１つ選び、続いて選択肢から１つを選んでください。やり直すときは、英語を選び直すことから始めてください。右の［単語帳］を参考にすることもできます。）The Japanese attack on Pearl Harbor ended the long American debate over whether to become involved in the Second World War. American politicians and citizens had argued for years about whether to remain neutral or to fight to help Britain and France and other friends.
Japan's aggressive attack at Pearl Harbor united Americans in a common desire for military victory. It made Americans willing to do whatever was necessary to win the war. And it pushed America into a kind of world leadership that its people had never known before.
President Franklin Roosevelt and his advisers had to make an important decision about how to fight the war. Would the United States fight Japan first, or Germany, or both at the same time?
Japan's attack had brought America into the war. And it had severely damaged American military power. But Roosevelt decided not to strike back at Japan immediately. He would use most of his forces to fight Germany.
There were several reasons for Roosevelt's decision. First, Germany already controlled much of Europe, as well as much of the Atlantic Ocean. Roosevelt considered this a direct threat. And he worried about possible German intervention in Latin America.
Second, Germany was an advanced industrial nation. It had many scientists and engineers. Its factories were modern. Roosevelt was concerned that Germany might be able to develop deadly new weapons, such as an atomic bomb, if it was not stopped quickly.
Third, Britain historically was one of America's closest allies. And the British people were united and fighting for their lives against Germany. This was not true in Asia. Japan's most important opponent was China. But China's fighting forces were weak and divided, and could not offer strong opposition to the Japanese.
Adolf Hitler's decision to break his treaty with Soviet leader Josef Stalin and attack the Soviet Union made Roosevelt's choice final. The American leader recognized that the Germans would have to fight on two fronts: in the west against Britain and in the east against Russia.
He decided it was best to attack Germany while its forces were divided. So the United States sent most of its troops and supplies to Britain to join the fight against Germany.
American military leaders hoped to attack Germany quickly by launching an attack across the English Channel. Stalin also supported this plan. Soviet forces were suffering terrible losses from the Nazi attack and wanted the British and Americans to fight the Germans on the west.
However, British Prime Minister Winston Churchill and other leaders opposed launching an invasion across the English Channel too quickly. They worried that such an invasion might fail, while the Germans were still so strong. And they knew this would mean disaster.
For this reason, British and American forces decided instead to attack the Italian and German troops occupying North Africa.