As the Trump administration begins to talk about a "Trump doctrine," it's worth remembering that presidential foreign policy doctrines paper over the fact that America enjoys extraordinary latitude when choosing how to interact with the rest of the world.
Marian Tupy writes:
We have been hearing a lot about the Trump Doctrine, lately. A week ago, for example, Reince Priebus, the White House Chief of Staff, said that "President Trump's decision to launch cruise missiles at Syria in response to a deadly chemical attack was part of a new 'Trump doctrine' governing his foreign policy." The president, Priebus continued, "is really establishing… a Trump doctrine in setting some certain lines of where we're not going to allow people like [Syrian President Bashar] Assad to go, but at the same time making it clear that we're not interested in long-term ground wars in the Middle East."
Whether Trump's foreign policy views amount to a coherent doctrine is doubtful. Let's not forget that candidate Trump railed against bombing of Syria when President Obama occupied the Oval Office. Similarly, Trump promised to declare China to be a currency manipulator on "day one" of his presidency, only to reverse himself later. Other flip-flops include Trump's attitude to Russia. The president, famously, wanted a good relationship with Putin, but soured on the Russian strongman following the U.S. bombing of Syria—Russia's ally. He also changed his view on the relevance and utility of the North Atlantic Treaty Organization, which he once saw as "obsolete," but now considers a "bulwark of international peace."
Of broader relevance, I think, is the existence of presidential doctrines in the first place. Since the Truman Doctrine at the start of the Cold War, America's foreign policy establishment, not to mention the rest of the world, awaits with baited breath the permutations of U.S. foreign policy each time America swears in a new Commander in Chief.