Recent presidential campaigns have not focused on foreign policy. This year could be different. The volatility of the international system has increasingly become intertwined with the domestic issues that tend to dominate presidential elections.

The civil war within Islam has produced the worst international terrorist threat of the modern era: ISIS, or Daesh. This conflict, as well as instability in Africa, has already pushed millions of migrants into Europe, which has given rise to greater nationalism and threatens the European project. Increasing terrorist attacks in the West—including the United States—call into question current counterterrorism strategies.

At the same time, slow growth and economic dislocation is producing a backlash against globalization. And against the backdrop of economic stagnation, isolationist sentiments in America are hitting levels unseen since the immediate post-Vietnam era.

Most significant, a major presidential candidate is challenging fundamental assumptions about U.S. foreign policy. Consensus behind a new grand strategy did not quite cohere after the Cold War. But presidential candidates since 1992, while differing on their approaches to specific issues, generally agreed that the U.S.-led postwar architecture should be preserved—and that American leadership was necessary to respond selectively to global crises and to keep the peace among major powers.

Donald Trump is different. Trump's pronouncements are more than an attack on Hillary Clinton’s worldview. Although stated in provocative and unorthodox ways, he takes issue with many of the tenets that have guided U.S. foreign policy across both Republican and Democratic administrations since the end of the Cold War. What we are witnessing is nothing less than the birth of a Trump Doctrine, one that calls for a break from the status quo on at least five main issues: U.S. goals, countering the terrorist group ISIS and Islamist extremism, democracy promotion, immigration and great-power relations.

U.S. Goals: Trump’s slogan—America First—harkens back to the isolationists of the pre-World War II era. Trump, however, is not an isolationist. Quite the contrary. He favors a large defense budget and wants to ensure that America remains the world’s sole military and economic superpower. Rather, “America First” is Trump’s way of attacking “globalism.” The term "globalism" encapsulates, for Trump, the myriad policies that he believes are expending American resources on behalf of goals incidental to core U.S. interests.

It is in the realm of international economics in particular that Trump is sounding the alarm of globalism. U.S. presidents since the end of World War II have taken the view that economic integration and free trade are win-win propositions that both further global security and benefit American interests, foreign and domestic. Trump’s America First view is more zero-sum and nationalistic. He believes that the United States naively practices free trade while other countries gain undue advantage through mercantilist practices. He believes many trade agreements have damaged America—negatively affecting U.S. workers and the middle class by facilitating movement of manufacturing jobs from the United States to other countries such as China and Mexico. He believes that these and related policies are producing slow economic growth, huge debt and undermining the underpinnings of U.S economic power.

Trump is intent on prioritizing U.S. economic interests. He, for example, will renegotiate NAFTA and abandon the current text of the Trans-Pacific Partnership in order to reassert U.S. sovereignty and protect and expand U.S. manufacturing and employment.

Countering ISIS and Islamic Extremism: Trump appears to see the threat of ISIS and Islamist extremism as urgent and the principal current threat to the United States. He believes that President Obama and candidate Clinton fail to recognize the nature of the problem—that ISIS and al-Qaida are Islamist terrorist groups—and accept that we have to live with the threat is unacceptable. He has said that a Trump administration will seek to defeat ISIS quickly and to eliminate its threat to the United States, rejecting the notion that we should learn to live with the threat. He wants U.S. alliances to focus on the threat of Islamist terrorism and also is willing to cooperate with Russia to defeat it. He is willing to use more U.S. forces and to adopt more aggressive tactics. He appears to favor using a lot of force against terrorist targets in the Middle East but then get out rather than maintain a significant role on the ground for years. He also wants to review U.S. immigration and visa policy as well domestic law enforcement policies to deal with this threat.

Immigration: Trump also departs from the establishment on both legal and illegal immigration. He wants to break the cycle of millions of illegals becoming legalized every few decades in deals that include commitments to control illegal immigration—commitments that always go unfulfilled. His often used imagery of a wall expresses the determination to break that cycle by whatever means are necessary.

On legal immigration, it appears that Trump would like to reduce the flow and perhaps change the criteria for who would be admitted. He argues that reducing and changing criteria for legal immigration would result in increased employment for Americans and legal residents, particularly in the lower end of the income spectrum. His concerns about ISIS using flows of refugees to infiltrate terrorists into the United States led him to call for suspending visas for all Muslims until a process was established for reliable vetting, which later he modified to temporarily suspending admission of visitors and immigrants from terror-afflicted countries.

Trump appears to fear Europe’s problems replicating themselves in the United States. In Europe, the continent is in the midst of a potentially dangerous paradigm shift. According to some estimates, more than 700,000 Africans are waiting in Libya to move to Europe, with millions more likely to follow their path given population growth and economic and political crises on the continent. This could eventually dwarf the already destabilizing current and future flows from conflicts in the Middle East and South Asia. This would inevitably have huge impacts in domestic politics and security in Europe.

Great-Power Relations: Trump is envisioning a new era of great-power relations. He favors a less truculent approach to Russia than Hillary Clinton. While other presidents have pursued common understandings with Moscow, Trump envisions perhaps a more sweeping paradigm shift—and perhaps a new grand bargain: acceptance of some kind of a sphere of influence for Moscow in parts of its immediate neighborhood in exchange for Russian cooperation on issues important to the United States with regards to war on terror, Syria, and the Asian balance of power. In his view of Russia, he may be closer to President Franklin Delano Roosevelt’s attitude toward the Soviet Union than the approach of any subsequent American president.

Due to strong pressure from Trump campaign officials, for example, the Republican platform dropped an endorsement of the provision of lethal defensive arms and assistance to Ukraine. Trump’s recent statement that called into question America’s guarantee to NATO allies under Article V if they are not meeting their own defense obligations created a furor. Trump made it clear that he wants to use it as a bargaining tool to force allies to pay for their defense, and has also stated that he wants to preserve NATO.

With China, by contrast, the Trump Doctrine would pursue a much harder line. He has promised to place China’s economic practices—its alleged currency manipulation, lack of intellectual-property protections, and economic espionage—at the center of the bilateral relationship. Economic pressure, Trump believes, would not only address U.S. domestic concerns—such as the loss of manufacturing jobs—it would also provide a means by which Washington could elicit Chinese cooperation on security concerns such as the North Korean nuclear program.

Great-power relations may also shift in the context of U.S. relations with its traditional allies. Trump is hardly the first American political figure to gripe about our allies' free-riding. What distinguishes Trump, however, is the degree to which he is consumed with the issue. While U.S. presidents have tended to accept freeloading as a price worth paying for a network of alliances that underwrites international security and preserves U.S. global leadership, Trump is prepared to wield U.S. leverage to ensure that U.S. alliances pay their “fair share.”

Democracy Promotion: Particularly since the Reagan years, democracy promotion has become a central tenet of U.S. foreign policy. Policymakers have generally reached the conclusion that the spread of democracy and human rights is not only consistent with American ideals, but also contributes to a more peaceful world. When military operations in Afghanistan and Iraq were undertaken to overthrow regimes posing serious security problems, bipartisan coalitions supported the installation of democratic governments to reestablish political authority. The consensus was that democratic ideals have universal appeal and can take hold across countries and regions with different histories and cultures.

When Trump alludes to democracy promotion, he does so mostly in the context of his sharp attacks on nation-building and regime change. In his Republican National Convention speech, for example, he lambasted the U.S. decision to support the overthrow of dictatorships in Iraq, Libya, Egypt and Syria, arguing that these efforts undermined stability and U.S. counterterrorism priorities. Trump pledged unequivocally to “abandon the failed policy of nation building and regime change.”

Trump is raising serious issues that deserve to be debated. How precisely would he pursue his vision at a practical level, and how would he minimize the negative, perhaps unintended, consequences of his proposals?

Achieving greater burden sharing and focusing our alliances on current threats would be positive. However, the challenge is how to achieve this goal without shaking confidence in the United States. It is clear that our current approach has not achieved the right balance both on updating the alliances and on burden sharing. But there is the risk that undermining confidence in the United States and its alliances could produce scenarios such as renationalization of security policies by great powers, similar to the situation before World War II, including the nuclearization of allied countries.

Trump has expressed sympathy, if not outright support, for nationalist forces in Europe. But he has not explained how these trends will redound to the benefit of the United States. It would not serve U.S. interests for the next administration to exacerbate xenophobic sentiments on the Continent through protectionism and incendiary rhetoric about burden sharing.

Revisionist powers such as Russia and China would become more aggressive as U.S.-led alliances weaken because they lose credibility. What would a Trump administration do to minimize such threats?

Even with a more accommodating policy toward Russia, we have to avoid undermining relations with European allies and compromising the sovereignty of states such as Ukraine and Georgia. Far from being a pathway to U.S.-Russia cooperation, there is the risk that the Trump Doctrine’s step back from Ukraine could open the door to further incursions by Russia against its European neighbors.

Given the current Chinese leader’s push for regional hegemony, the United States needs a balance of power approach in Asian security—with Japan, India, Vietnam and other regional power playing a balancing role and the U.S. as the ultimate balancer. How would a Trump administration engineer this balance?

After World War II, the United States underwent a paradigm shift in its foreign policies—remaining deeply engaged in unstable regions to maintain great-power peace. To develop the details of this new paradigm, the Truman and Eisenhower administrations developed some of the most important internal and external institutions of the Cold War era. They also engaged in bipartisan deliberations involving leaders of both the executive and legislative branches, drawing on expertise from inside and outside of government. Such a process to arrive at a bipartisan consensus is necessary regardless of who becomes our President.

Trump’s critique of free trade has its merits. It takes inordinate time and expense for American firms to document and litigate unfair trade practices such as dumping under the current process. The risk is that by the time they secure a judgment, their mercantilist competitors have harmed them irreparably. And there has been no response to the problem of currency manipulation. However, Trump needs to articulate how he would design a more effective enforcement process for trade agreements and how he would avoid rounds of tit-for-tat retaliation leading to trade wars. As many have said, America has 5 percent of the world’s population, and its prosperity depends on selling to the other 95 percent.

On immigration, it is certainly time for a review of not only whom we allow into the country, but who especially we wish to attract—the best and the brightest from around the world and individuals who subscribe to America’s core values. An updated immigration strategy is required, and control of the border and who comes to the country is also a must, as is developing a system to police visa overstays. The global population movement makes this necessary. We need to work together with our European allies to assist them in developing appropriate strategies for the coming potential flood of refugees and the future of Africa as an urgent matter.

Yet, Trump’s sometimes inflammatory rhetoric has undermined his ability to work with all groups in American society on this question. As a candidate and, if he wins, as a president, he must shed this divisive approach, which is counterproductive to finding the needed consensus on a way forward.

On democracy promotion, I judge that the goal of a democratized world as a long-term objective remains valid. But how this goal is pursued, especially given recent setbacks, is an important question. It needs to be debated recognizing that the process of building an effective liberal democracy takes time – as it did in our own country. The path to open political systems will vary according to the different histories, cultures, and circumstances of our partners. It requires us to work patiently with leaders and societies of aspiring democracies and not to abandon them when they experience setbacks.

On strategy and tactics, perhaps a differentiated approach would be the best. We should emphasize stability and conflict resolution in places such as the Middle East and Africa. We should work to consolidate democratization in other regions such as parts of Europe, parts of Asia and the Americas, where democratic institutions have faltered. Also, it would be beneficial to review whether our institutions involved in democracy building are effective and make the necessary reforms.

On countering Islamist terrorism, notwithstanding his refusal to engage in nation-building and keep to get involved in protracted conflict and policing, Trump has vowed to destroy ISIS within a matter of months. If his intent is to liberate ISIS-held areas such as Mosul in Iraq and Raqqa in Syria, the question is how he will do so. A good option is to follow the Afghan model, embedding U.S. and coalition Special Forces with local fighters and applying significant air power against ISIS targets. However, the question of what happens to the areas liberated from ISIS must be answered. How, without state-building and new power-sharing arrangements in Iraq and Syria, would a Trump administration prevent segments of the Sunni Arab population from gravitating to yet another (and perhaps even more vicious) terrorist group? After all, ISIS is the successor to the terrorist group Al Qaeda in Iraq. There is also the broader question of how to change failed policies in dealing with state sponsors of terrorist and extremist groups such as Pakistan.

Even if we avoid large state- and nation-building projects such as Iraq and Afghanistan, we need to preserve the capacity, acquired at enormous cost based on experience in Iraq and Afghanistan, to assist in limited state building to help friendly forces control territories which have strategic value. Not doing so would mean overlearning the lessons of Iraq and Afghanistan and risk creating vacuums in which terrorists could establish sanctuaries. Such a mistake, in turn, might require a larger intervention and occupation of such territories to root out terrorist forces, as happened after 9/11.

The objective of getting Russia to work with us to defeat ISIS is desirable—but there is no guarantee that Moscow will do so. Previous efforts at achieving U.S.-Russian cooperation by Bush and Obama administrations have not succeeded. What is the basis for Trump’s confidence that he will succeed if and when he is the U.S. president?

It is imperative that the Trump campaign not leave these questions unanswered. This is because Trump’s fundamental critique has merit: America’s challenges at home—driven by unprecedented debt, weak economic growth, racial and class divisions, and growing economic inequality—do indeed threaten U.S. primacy abroad. He has raised these issues in a uniquely provocative manner. His boldness must now be matched with wise solutions.

Trump speaks for millions of Americans with his unfettered attacks on an establishment that has, in fact, made its share of errors. For this, he has been awarded the Republican nomination for president. Now, just three months before his possible election as Commander in Chief, he has our attention. It is time for him to pivot to a more serious dialogue with more details on how to deal with these issues. Regardless of the outcome of the general election, the issues that he has raised and the sentiments to which he has lent his voice are not going away.

Zalmay Khalilzad is a Counselor at CSIS. He was the US Ambassador in Afghanistan, Iraq and the UN. He is the author of a new book: The Envoy: From Kabul to the White House: My Journey through a Turbulent World. St Martin's Press.

Image: Donald Trump speaking in February 2016. Photo by Marc Nozell, CC BY 2.0.