The presidency of Donald Trump is based on the idea that he and the United States are powerful enough that both allies and enemies must submit to his will. This approach is a break from decades of US foreign policy doctrine. Trump's philosophy is being tested in growing confrontations with certain countries.

A key advisor to Trump has explained this approach as being governed by force and power. The idea is that the US is so strong that others must comply with its demands.

Further details on these developments are available from the source, including analysis by Stephen Collinson, CNN.