In most cases, it is nearly impossible to say. Because Mr Trump's policies are so unusual and his election victory so unexpected, foreign nations have not indicated how they might respond. So it difficult to judge even the first order effect of say, a Nato withdrawal or a partnership with Assad in Syria, much less any ripple effect. In practise, much of foreign policy is responding to crises. Mr Trump's lack of experience or clear proposals make it difficult to predict how he would handle, for example a major breakthtough in North Korea's nuclear programme or a major russian cyberattack. NYT