The whole world is struggling to decipher the worldview and guiding principles Republican candidate Donald Trump would apply as president. It may not be a prominent feature of his campaign, but his advisers say he does have a doctrine that informs his positions on foreign policy and national security.

Some leading pundits are convinced Trump is shooting from the hip on foreign policy, making up glib answers to serious questions like how to defeat the Islamic State or deal with an aggressive Vladimir Putin. Top Republican national security officials who advise other candidates routinely tell reporters they have not heard from the Trump campaign, which leads them to believe he has not sought any expert input before his provocative statements, like lashing out against China or Saudi Arabia.

Trump's advisers say they're happy to be perplexing. The Washington foreign policy establishment has no idea what to make of Trump's string of declarations, such as his promises to "take" the Islamic State's oil, force Mexico to pay for a wall on the southern U.S. border, or bar all Muslims from coming to the U.S.