研究國家外交行為暨政策者眾多，但翻查文獻卻極少見到關於「斷交」之學理分析。然而，某些國家（例如卡達）或是具有爭議的政治實體（例如台灣）在與其它正常主權國家進行互動時，確實可能面臨它國不願與之建立正式邦交或甚至選擇與之斷交的命運。鑑此，本文提出一個值得思考的研究問題—「具有法律上邦交關係(de jure type)的兩國（或政治實體）是否比起欠缺此種關係的兩國（或政治實體），在實質外交互動(de facto type)上更為頻繁或熱絡？」為了回答上開研究問題，本文對聖多美普林西比、巴拿馬、多明尼加、布吉納法索、薩爾瓦、索羅門群島、吉里巴斯等七國與台灣（中華民國政府）和北京當局（中華人民共和國政府）的雙邊貿易互動進行逐一檢視與比較，發現具正式邦交關係的雙方未必有實質且不可或缺之貿易往來；同時，真正基於需要而展開的貿易往來鮮少會因為法律上邦交關係的中斷而一併停止。「邦交」因此有必要和「外交」（經貿面向的）進行區別；台灣斷交國數目的增減與其實質外交的表現沒有必然之因果關係。 Despite the prevalence of studies on foreign policyand its decision-makers, studies that analyze severance of diplomatic ties are rarely seen when searched. As a matter of fact, certain countries such as Qatar or debatable political entities such as Taiwan might reluctantly fail to establish diplomatic ties or fail to maintain diplomatic relations when interacting with other sovereign states. In light of these events, this paper proposes a thought-provoking research question-Is the interaction between two countries (or political entities) that are de jure type allies more frequent than theinteraction between two countries (or political entities) that are de factoone? To answer this question, this paper examines and analyzes the bilateral trade interaction between Taiwan (the Government of the Republic of China) and each of its seven former de jur ediplomatic allies respectively, including Democratic Republic of Sao Tome and Principe, Republic of Panama, Dominican Republic, Burkina Faso, Republic of El Salvador, Solomon Islands, and Republic of Kiribati, to compare the bilateral trade interaction between Beijing (the Government of the People's Republic of China) and these seven countries who are now Beijing's de jure diplomatic allies. This paper finds that trade interaction between two de jure allies might not be truly essential or consequential. Meanwhile, trade interaction based on actual needs is rarely ended because of severance of a diplomatic tie between two formerly de jure allies. The differentiation between a de jure diplomatic tie and a de facto diplomatic interaction is therefore necessary. The increase or decrease in the number of Taiwan's de jure allies does not necessarily reflect Taiwan's actual diplomatic performance. In other words, there is no obvious causality.
