1940年夏季，法英兩國在歐戰劇變和日本施壓的背景下，先後封閉了中國抗日物資的主要通道，致使中國的抗日戰爭遭遇到為期3個多月的極其深刻的國際危機。本文依據《蔣中正日記》手稿本及其他相關史料，分6節考察了他對這一危機的處置過程，指出其可以概括為下述特點：（一）整體：惟以日本為敵，與日本以外的所有國家都加強友好。（二）對德：結束歐戰爆發以來的疏遠狀態，力求在維持中英美友好關係的前提下獲得改善。（三）對日：檢討和戰的利害得失，並在至少確保最低條件下試探媾和的可能性。（四）對歐戰及相關國家：克服國民政府領導層中出現的偏激情緒與極端意見，同時看到多種可能性，並相應準備多種因應措施，等局勢明朗化後再做最終決斷。文章還認為，對日本政策走向的觀察和對德、蘇、英、美相互關係發展趨勢的展望，是影響蔣中正決策的兩個關鍵，而在此二者中所反映出來的蔣的哲學思辨，則表現出他比其他人高明的地方。

In the summer of 1940, Britain and France, deeply involved in the European war blocked China's main channels to obtain strategic goods from abroad under the pressure of Japan. As a result, China, in the middle of the war against Japanese invasion, encountered a serious international crisis lasting for three months. Based on Chiang Kai-Shek's diary and other historical materials, this paper describes how Chiang dealt with the crisis in 6 sections and concludes with the following points: (1) In general, China must take Japan as the only enemy and strengthen ties with any other country; (2) end the frosty relation with Germany after the breakout of the war in Europe and forge better relations with it while maintaining friendly relations with Britain and America; (3) analyze the merits and demerits of peace or war with Japan and seek the chance of peace with the minimum requests accepted; (4) regarding the European War and the countries involved: suppress the extremists' opinion among government's leadership, and take no side in Europe until the end. The two key factors that led to Chiang's decision are his observation of Japan's policy and his judgment of the current and future relations among Germany, USSR, Britain and America. This article also demonstrates that Chiang's political philosophy as seen in the process of dealing with this crisis is superior to others.