美國如何操作外交政策訊號而使其政策意圖能夠被正確解讀呢？過去研究探討美國外交政策是否因「聽眾成本」大小而變得可信。但對於美國政府如何操作外交政策訊號卻未有系統性研究。本文介紹過去學界引用賽局理論所推演出的兩項假設。即在高賭注系列事件上，美國外交政策訊號呈現正反夾雜，混淆不一的現象。而在低賭注系列事件，美國政策訊號則呈現重複敘述，單調一致的現象。本文以美國在南海島礁爭議，以及其在APEC承諾的系列事件為例，試圖檢證上述兩項假設。本文發現就此兩系列案例，美國政策訊號操作與理論預期相符。 How does the U.S. manage its foreign policy signals to ensure its intentions are read correctly? Scholars have invoked the concept of ‘audience cost’ to explain credibility of leaders’ threats and policy signals. However, no systematic study has been undertaken on how the U.S. government manages its foreign policy signals. By employing two hypotheses developed by a scholar of signaling games, this paper attempts to examine how the U.S. manipulates policy signals to allow its intentions to be read correctly. Specifically, this paper posits that if the U.S. is enmeshed in a series of high stake events, it will adopt a mixed strategy, sending out positive and negative signals after each other to balance the perceptions of ‘threat’ with those of ‘reassurance.’ If it is involved in a series of low-stakes events, however, the U.S. adopts a stance of ‘cheap talk’ to reiterate policy content, thus giving consistent signals. Two cases are used to test these hypotheses: U.S.’ involvement in disputes in the South China Sea and its APEC commitments.