Donald Trump has now officially taken over the reins of American foreign policy, after having done so less officially (mostly via Twitter) during the transition. Prediction is a dangerous game, and, as many observers have noted, Trump’s comments on foreign policy have been anything but consistent thus far.

Even so, I think we can discern the broad outlines of an emerging Trump Doctrine. Three key themes, in particular, will shape Trump’s decision-making on foreign policy.

The most fundamental pillar of the doctrine is Trump’s “America First” nationalism. It is a rejection of the idea that the U.S. is obligated to worry about the rest of the world.

Although Republicans and Democrats spend a lot of time criticizing each other, foreign policy leaders from both parties have generally been in agreement since 9/11. They see the fundamental goals of American grand strategy as preserving American primacy, while meddling incessantly around the globe to produce outcomes seen as beneficial to U.S. security and to global order.

Trump, on the other hand, views foreign policy not primarily as the art of providing global public goods such as peace and stability, but instead as a series of negotiations in which the goal is to get the best possible deal.

Understanding this helps explain many of Trump’s unorthodox, and apparently inconsistent, positions.

Because Trump does not have an ideologically driven desire to play the role of world’s policeman, he takes a skeptical view of military intervention. He shocked many observers, for example, when he broke with his fellow Republicans and called the Iraq war a terrible mistake. He has also repeatedly rejected both regime change and nation-building as useful tools of U.S. foreign policy. Similarly, where many view the U.S. as benefitting from efforts to provide global stability and security, Trump instead sees the U.S. getting suckered for little or no return. Though he has walked back his most critical comments about the U.S. role in NATO and in the Pacific, it is clear that Trump sees little obvious gain from most of America’s historical alliances.

Trump’s rejection of past military interventions, however, does not mean he is a dove. In fact, the second emerging pillar of the Trump Doctrine is militarism.

Trump’s nomination of generals to top security posts illustrates Trump’s appreciation for military strength, as does his promise to “rebuild our military.” And even though Trump believes that large-scale military intervention tends to generate low returns, his support of torture and his promises about “smashing ISIS” suggest that he will embrace aggressive military solutions under certain conditions.

The third pillar of the Trump doctrine is economic nationalism. Abandoning decades of orthodoxy on international trade, as well as the views of his own party, Trump made clear throughout his campaign that he believed the U.S. needs to take a more active role in protecting American industries and workers. Trump has repeatedly threatened China with retaliation for unfair trade practices and tweeted out threats of tariffs on auto manufacturers who outsource jobs and build factories abroad.

Making this pillar even more important is that, where other presidents have viewed the main task of American foreign policy as security related, Trump sees the main task as an economic one. Trump has complained about the U.S. not getting paid enough for protecting its allies, argued that the U.S. should have taken Iraqi oil after the 2003 war and repeatedly declared that the U.S. is too poor to take care of the rest of the world. Trump’s nominee for secretary of state, Exxon CEO Rex Tillerson, whose primary qualification is his long career of cutting major business deals around the world, makes it clear that economic issues will shape U.S. foreign policy far more than they have in the recent past.

The Trump Doctrine will represent a significant break from the past generation of American foreign policy-making, for good and for ill.

On one hand, many worry that Trump’s rejection of liberal internationalism and free trade foreshadows a new era of American isolationism and a threat to world order. On the other hand, Trump’s disinterest in military adventure suggests he will end America’s unpopular and counterproductive intervention in the Middle East.

And although Trump’s penchant for creating foreign policy on the fly has already heightened tensions with allies and adversaries alike, his dismissal of the “Washington playbook” gives him the freedom to rethink alliances and strategies long overdue for re-examination.

Time will tell how the Trump Doctrine plays out, though, in the meantime, it might be better to check Trump’s Twitter feed for clues.