对冷战后《美国国家安全战略报告》的文本分析

A Text Analysis of the U.S. National Security Strategy after the Cold War

《美国国家安全战略报告》(下文称报告)是冷战末期以来美国历届政府阐述其国家安全战略的重要文件,历份报告体现了美国国家安全战略的发展演变,其中2017 年特朗普政府发布的报告首次在冷战结束后将大国竞争列为国家安全的首要威胁,该报告被认为对美国安全战略进行了重大调整。然而,既有文献对美国国家安全战略调整原因的解读不一,国际局势的变化、国家利益的调整与总统党派更迭成为三种可能的解释。本文对历份报告进行词频统计,将报告中的高频词汇按照对战略环境的判断、对国家利益的认知、对国家安全威胁的识别、对战略手段的选择等组别进行分类,并按时间顺序整理这些数据,得出历份报告的词频变化图谱,以此对美国国家安全战略转变原因展开研究。研究发现,美国政府对战略环境的认知的改变构成了美国安全战略调整的主要原因,其中重大事件对战略环境判断的影响直接而明显。与其对战略环境判断的多变性相比,美国政府对由军事安全、经济繁荣与价值观作为其主要的构成要素的国家利益的界定具有稳定性。总统个人党派背景对国家安全战略的影响体现在对战略手段的选择上,并不构成导致国家安全战略转变的动因。

The National Security Strategy of the United States (hereinafter, the report) is an important document in which the U.S. government outlines its major national security strategies beginning from the late 1980s. The reports reflect the development and adjustment of the U.S. national security strategy. What is new about the 2017 report by the Trump administration is that for the first time in the post-Cold War era, it identifies competition from great powers as the primary security concern. However, the existing literature fails to reach a consensus on the main cause of the adjustments of the U.S. national security strategy, offering instead three possible explanations: changes in the international environment, different perceptions of national interests, and shifts in the partisan affiliation of the presidents. To determine which is the crucial factor, this paper conducts a text analysis of all reports published to date. It first counts the frequencies of specific terms in the reports, then classifies them into different categories such as the assessment of the strategic environment, the perception of national interests, the identification of national security threats, and the selection of strategic means. Finally, frequency graphs are produced by chronologically presenting data from each report. This study finds that the U.S. government’s perception of the strategic environment constitutes the main reason for the adjustments, and major events have a direct impact on the government’s perceptions. In contrast, the government takes a relatively stable view of national interests, consisting of military security, economic prosperity and values. The partisan affiliation of the President is also not a cause of the adjustments of the national security strategy, although it has an impact on the choice of strategic means.