[ad_1] <br><img src="https://assets.realclear.com/images/52/521797_1_.jpg" /><br>September 18 marks one year since National Security Adviser Robert C. O'Brien began his tenure. <br>[ad_2] <br><a href="https://www.realclearpolitics.com/2020/09/20/obrien_and_trump_score_a_year_of_international_triumphs_523840.html">ABCNews</a>