At noon on January 20th, Barack Obama stepped aside, leaving Donald Trump as the leader of the free world. In his inaugural address, Trump pledged to implement an ‘America First’ doctrine. But while the implications for trade and immigration are relatively clear, his speech brought us little closer to understanding what this will mean for foreign policy.

Indeed, thanks to the incoherence of the president-elect’s foreign policy remarks during his campaign, the range of potential outcomes is wide. But Trump’s past comments suggest four potential paths that his ‘America First’ Doctrine could take.

The first option is true isolationism. Though it remained unclear throughout the campaign the extent to which Trump truly understood the historical baggage that came with the term ‘America First,’ many commentators assumed that he would indeed pursue a classic isolationist policy. And Trump seems to mean it literally in some cases: only a week into office, he has already sought to erect trade and immigration barriers. He may also seek to withdraw from the world in military terms, abandoning alliances, and refusing to engage in even the diplomatic resolution of international problems which don’t directly concern the United States.

Yet elements of Trump’s own statements call this assumption into question. From his insistence on increased military spending to his promise in the inaugural address to eradicate radical Islamic terrorism ‘completely from the face of the Earth,’ Trump has repeatedly implied that he is likely to pursue a relatively hawkish foreign policy.

A second option for the Trump Doctrine could be described as ‘pragmatic power.’ In his rare scripted speeches devoted to foreign policy, Trump’s speechwriters did a good job of working his off-the-cuff remarks into a relatively coherent and pragmatic approach to the world.

While unscripted Trump calls NATO ‘obsolete’ and a rip-off, for example, his speeches highlighted the need for wealthy allied states in Europe to pay more towards their own defense. Rex Tillerson, Trump’s nominee for Secretary of State, seems to share this worldview, noting in his confirmation hearings that his background as an engineer leads him to seek logical solutions to international crises.

Yet this level of coherent pragmatism appears unlikely given Trump’s own reactive personality. Intensive efforts by aides to reshape Trump’s inflammatory statements into a broader, saner critique of flawed U.S. democracy promotion and regime change efforts are often swiftly undone by the President himself. Within one day of his inauguration, for example, Trump reiterated his remarks on ‘taking the oil’ while visiting the headquarters of the Central Intelligence Agency.

A third option for Trump’s America First Doctrine is thus a far less pragmatic ‘global crusade.’ Drawing on the views of key advisors like Michael Flynn and Steve Bannon, Trump could instead embrace a ‘clash of civilizations’ approach to the world. This would subordinate all other foreign policy crises to a campaign against radical Islam, a philosophy that he and various advisors believe includes elements as diverse as Iran, al Qaeda, ISIS and the Muslim Brotherhood.

Indeed, in his augural address, Trump promised to “unite the civilized world against radical Islamic terrorism.” To that end, Trump’s conciliatory approach to Russia – in which he often cites terrorism as a key joint concern – suggests a willingness to work together on counterterrorism.

However, it remains uncertain whether Trump – not known for his cerebral qualities —will explicitly pick any such coherent strategy. Instead, the ‘America First’ doctrine that appears most likely to emerge is a reactive form of Jacksonianism, or a modified version of Reagan’s ‘Peace Through Strength.’

Such a strategy would take a more hands-off approach to global affairs, and enact substantive trade and immigration restrictions. But at the same time, it would follow through on Trump’s promises to rebuild and expand the U.S. military, increase military spending, destroy ISIS, expand the military’s rules of engagement, and take a reactive, hardline stance on Iran, China, nonproliferation and a host of other issues any time he feels that America’s honor is threatened.

The differences between these four potential Trump Doctrines cannot be overstated, yet all four remain politically viable paths, a testament to the campaign’s scattershot foreign policy pronouncements. And the internal politics of the incoming administration – where advisors appear to have a dizzying selection of different views – also matter. Trump’s inaugural address – apparently written by Steve Bannon – may only reflect one faction within the administration.

Trump’s inaugural address provided a name for his foreign policy doctrine, yet its content remains largely a mystery. Few presidents have ever come to office with so little background in governance and so ill-defined a foreign policy worldview. A rocky first week, filled with crises, has only exacerbated the confusion. Only as President Trump begins to settle into his new role will we finally start to learn which ‘America First’ doctrine we can expect for the next four years.