北约东扩是影响俄罗斯与美欧关系以及未来欧洲安全格局的一个重要因素。北约东扩所引起的欧洲政治安全边界的改变、在欧洲地区部署的反导武器系统，以及最近所部署的相当规模的常规军事力量，这“三位一体”的进程不可能不引起重大争议。在 2017 年慕尼黑北约峰会上，美国开始逐渐摆脱“大选效应”，重新表示支持与北约的盟友关系。但是，俄、欧、美三者之间的立场依然相互分殊，北约、俄罗斯和欧洲安全关系的前景依然扑朔迷离。今天的北约东扩是否会重蹈历史上西方扩张的覆辙：由一元主义的追求为起点，最后总是落得多元力量并存的结局，是一个值得作进一步观察的向度。

The NATO’s eastward expansion is an important factoraffecting Russia-U.S. relationship and European future security configuration.The changes in political and security borders of Europe caused by the NATO’s eastward expansion, the deployment of anti-ballistic missile systems in Europe, together with the conventional military forces recently deployed, are bound to arouse heated controversies. Although at the 2017 NATO Summit in Munich, the United States reiterated its support for alliance with the NATO, which illustrates the U.S. has already begun to gradually get rid of the “presidential election effects”. The U.S. has returned to maintaining its traditional position of relations with the North Atlantic allies. Nevertheless, it’s yet to be observed whether today’s NATO’s expansion will repeat mistakes of the past, that is, beginning with pursuing monism but finally ending with co-existence of multiple powers.