In mid-1940, President Franklin D. Roosevelt moved the Pacific Fleet from San Diego to Hawaii. He also ordered a military buildup in the Philippines, taking both actions in the hope of discouraging Japanese aggression in the Far East. Because the Japanese high command was (mistakenly) certain any attack on the United Kingdom's Southeast Asian colonies, including Singapore, would bring the U.S. into the war, a devastating preventive strike appeared to be the only way to prevent American naval interference. An invasion of the Philippines was also considered necessary by Japanese war planners. The U.S. War Plan Orange had envisioned defending the Philippines with an elite force of 40,000 men; this option was never implemented due to opposition from Douglas MacArthur, who felt he would need a force ten times that size. By 1941, U.S. planners expected to abandon the Philippines at the outbreak of war. Late that year, Admiral Thomas C. Hart, commander of the Asiatic Fleet, was given orders to that effect.