Rather than telling Japan that the US was determined to search for a diplomatic solution, America’s categorical reaction confirmed it to the Japanese as an arrogant and conceited enemy. Moreover, by transferring its Pacific Fleet from San Diego to Pearl Harbor, the US encouraged the Japanese understanding that the US fully anticipated war with Japan.
日本军队攻入东南亚导致美国总统罗斯福当局实行制裁。美国冻结了日本的资产，英国和荷属东印度也随后效仿。日本通过占领法属印度支那南部还以颜色，美国则对日本实行石油禁运予以报复。美国不仅没有告诉日本它决心寻求外交解决途经，其坚硬的反应措施使得日本确信美国是一个自负的敌人。而且，美国将太平洋舰队从圣地亚哥转移到珍珠港，促使日本认为美国完全打算与日本开战。