Because the national strength and geographical position of the United States are very important, in addition to Germany, only a few countries with a large population, such as the United States and Russia, can quickly form a huge army of more than five million people, while the quality of American soldiers is the highest in addition to Germany, and the technological level, industrial development and economic strength of the United States. If the United States does not participate, it will be a major loss for the big alliance. Another point is that the geographical position of the United States is very important to the combat effectiveness of the Grand Alliance Disintegration Army in Central America. Today, Panama, Haiti, Nicaragua, Colombia, and other Central American countries are almost awed by China's strength and have taken refuge in China's embrace. China has a large number of military bases and combat personnel in these countries. If we rely solely on sea attacks, it will be difficult for the allied forces to achieve greater results in a short period of time, and the rapid opening of the Panama Canal will be of great strategic significance for the allied forces to enter the Pacific from the Atlantic Ocean, because if they go around the southern tip of South America to the Pacific Ocean, the supply line will be very long,smart board interactive whiteboard, and the war will become very difficult. China, on the other hand, has a large number of supply points on the Pacific coast, which will be a huge disadvantage for the alliance navy to prepare for sustained combat. Today, Egypt's Suez Canal, the throat of the Mediterranean Sea leading to the Indian Ocean,smart boards for conference rooms, seems to be under the joint control of Germany and Turkey, but Turkey is a strong representative of the pro-China faction. In wartime, the Chinese carrier fleet in the Mediterranean Sea and the fleet in the Indian Ocean will soon control the Suez Canal and cut off the close connection between the European continent and the Indian Ocean. At that time, it will be difficult for the Alliance Army to transport troops and supplies to the Pacific and Indian Ocean battlefields. So if the United States is involved, then the huge ground forces of the United States will sweep across Colombia, Nicaragua, Panama and other Central American countries from north to south, quickly occupy Panama, control the life transportation line of the Panama Canal, and allow the strategic materials and forces of the alliance forces to quickly reach the Pacific region. Then the Alliance forces can gradually attack Hawaii and China-controlled Australia and Southeast Asia based on the United States and Central America. After seizing these areas, the Alliance forces will attack China from all directions together with the Indian and Russian forces. Another country that Hitler did not tell Roosevelt about, Japan, was also interested in joining the alliance. Japan has been controlled by China for many years and has lost its complete sovereignty and independent economic and technological development status. The resentment in the hearts of the Japanese has gradually accumulated for many years. According to the psychology of the Japanese, 86 smart board ,digital touch screen board, the Germans have already made secret contacts with Japan. In wartime, Japan will probably become one of Germany's allies and participate in the encirclement of China. If the allied countries occupied Japan, their troops would have a foothold, and a large number of strategic materials could be transported to the front line through Japan, and then the allied troops could land on the Korean Peninsula through the Tsushima Strait and join forces with the Russian army to attack Siberia and northern China. Therefore, with the United States and Japan, the probability of victory of the allied forces will be greatly increased. The progress of the war and the speed of victory will be very crucial, because China's nuclear test has achieved great success and will soon produce nuclear bombs in the next few years. Therefore, Hitler's plan mentions the issue of quick victory in the war. Hitler believed that if the Allied forces did not win within three years, their fate would become very tragic once China developed a nuclear bomb. Obviously, the war would turn into a one-sided massacre. Even if the Allied forces were not completely wiped out, they would have to return to the mainland, accept the fate of defeat and accept the harsh armistice conditions put forward by China. For this reason, Hitler specially formulated a new strategy for this war, which is called Blitzkrieg, that is, the war should be launched quickly, the advance should be swift and violent, and it must not be sloppy. Once the war starts, it is necessary to use all the national strength to devote itself wholeheartedly to it and make up its mind to fight the war to the end. It is also necessary to give China a surprise, so that China can not react in a short time. Thus losing the initiative in many battlefields. After completing this secret meeting with Hitler, Roosevelt's heart began to be filled with a heavy thought, which did not disperse for a long time. After seeing Hitler off, he went straight to the office, lay quietly in his chair for a moment, and then thought carefully about Hitler's words. His eyes were uncertain, with both surprise and anxiety. His mood was quite complicated. The shadow of the defeat of the previous World War made Roosevelt's memory fresh. As one of the promising young people in American society at that time, Roosevelt felt deep pain under the clouds and humiliation of the defeat of the United States. This painful feeling left a heavy burden in the hearts of Americans like Roosevelt. After the war, Americans reflected that it was a wrong choice to launch this war. If the United States had not been involved in the European War and faced China directly, it might have become China's best ally and been able to obtain China's best technical support, which would have ushered in decades of great development for American society. But now, because of this wrong participation in the war, the economic and industrial level of American society has stagnated, and the 20-year golden period of development that it should have has come to naught. It has been caught up by Germany, Turkey and other countries. It has lost its status as the first industrial power in the capitalist world, and has fallen behind China and Germany, which is not much better than Turkey. So for Roosevelt, it would be a rather difficult process to make such a major decision. He had to consider comprehensively what kind of tremendous impact the war led by Germany would have on the whole world, what kind of position the United States would be in in the war, whether it could win the war,75 inch smart board, and how many national interests it could gain or lose after the war. He also has to consider how strong the opposition of the people at home is, whether there will be many opponents in the government and parliament, and whether people are willing to get involved in a world war again. There are many uncertainties.