The originality of this study does not lie in its topic, Trump and American security, but in the analysis and perhaps the conclusions drawn from it. Presidents are crucial to the foreign and defence processes of the United States and the resulting policies have a huge impact on the rest of the world. Accordingly, it is important to come to grips with the man making decisions in the White House. After Donald Trump's first year in office, this need has not diminished. A time-honoured analytical scheme suggests that Trump is a so-called 'activenegative' presidential type. In short, this means that he wants to be prominent but is uncomfortable with his office and its responsibilities. While Trump's foreign policy is often referred to as populist his strand of security policy does reflect an established tradition in American foreign policy. Just not one that has had a significant impact in the last 70 years. Trump will focus on those international problems that have a direct impact on the security of Americans in the US, since these are the kind of foreign policy problems that resonate with his voters. The Trump-administration will most likely face significant challenges, since the present changes in the international system appear to be the most significant since the end of the Cold War. Trump's unique brand of negotiating might surprise many and prove to be suited to a world of zero-sum politics. Trump is controversial not only overseas but in the US as well. Accordingly, the American system of checks and balances might curtail not only his politics but might also decrease the stature of the presidency. Since a strong executive power has been associated with an increase of American commitments abroad it might be assumed that a less powerful executive in the future might result in a US less committed to international security. In the long run this means that allies and partners of the US might have to handle a world that becomes less stable if the US no longer is ready to safe-guard the American world order.