Writing about foreign policy in the 2012 election means traveling second class, or even in steerage. To assess the diminution of foreign policy as an issue in U.S. politics, one need merely note that participants in the endless Republican primary debates turned to the topic only when attacking President Barack Obama or seeking relief from “social issues.” But the world won’t go away, and the United States, for reasons both moral and practical, cannot simply abandon world politics while we debate social issues and try to fix the economy.

To understand the content of any given foreign policy, it is useful to begin with the domestic context in which it is formulated. Here in the United States, that context is shaped by the psychic and political burdens of a decade of war and five years of financial crisis and recession. Those burdens have left large parts of the electorate exhausted and wanting a break from foreign entanglements. As a result, our foreign policy right now is focused on how to close out the Afghan war and direct national resources toward challenges of unemployment, debt, foreclosures, and investment. This focus marks a change in the way domestic priorities and foreign policy are now broadly seen. In the past, expenditures for national security were off limits when spending cuts were required. Now, however, $500 billion is proposed for defense cuts over the next decade, and many believe deeper cuts will be necessary to ease the budget deficit. So the U.S. role abroad will be played with fewer resources and less public support for an expansive foreign policy.

What kind of world will that reduced role be played in? Two major shifts have occurred in the way scholars and diplomats view the international system. For centuries the fundamental diplomatic calculus was made in terms of states, their interests and their powers; individuals had no place in it, and other collective entities a severely limited one. This traditional analysis fails to capture the world of today. Citizens now possess recognized human rights that require respect by states; transnational entities—economic, cultural, professional, and religious—have standing and influence; and international institutions exert their own significant influence. Meanwhile, understanding the relations among states requires a new approach. How will states manage cross-border conflicts in the post-9/11 world? What are the major threats to stability and the possible roads to peace and justice? Such questions are matters of much debate. Let me look at three levels of world politics containing issues of principle, moral as well as political, that will face the United States in the coming months and years.

First are interstate relations, which remain the heart of foreign policy. Of the various foreign vexations currently besetting the United States, Iran is the most time sensitive—and has become a principal way for Republicans to criticize Obama’s policy. The principle at stake, nonproliferation, defines rights and obligations in a world of nuclear weapons. It mediates between have and have-not states while seeking absolute denial of such weapons to non-state actors. The attempt to close the ranks of the “haves” to new members has been breached by four states (India, Pakistan, Israel, and North Korea) in the past two decades, and each potential new breach sends shudders through the system, especially if the new contender has a strongly ideological foreign policy. Hence the alarm raised by Iran, whose foreign policy includes aspirations for a hegemonic role in the Persian Gulf, an adversarial role against U.S. policy in the Middle East, and a declared objective of eliminating Israel as a state.

The policy choices facing the United States are prevention, elimination, or containment of Iran’s nuclear capability. Prevention is being pursued by the Obama administration in partnership with the other nuclear states on the UN Security Council. Elimination is the assumed policy of Israel; essentially a policy of preventive war, it resembles President George W. Bush’s approach to Iraq. Containment, which can be pursued in tandem with prevention, implicitly admits that the United States will not go to war to prevent Iranian nukes. In my view, the case for military intervention as a leading option fails to convince on either moral or strategic grounds. Would I rule it out in every case as “intrinsically evil”? I would not; but intervention should remain quite far down the list of options.

Interstate conflict and the threat of nuclear weapons are legacies of the Cold War era. But the 1990s produced a different kind of problem: internal conflicts in states and subsequent calls for humanitarian military intervention. The conflicts raged from the Balkans to Africa; more recently, the Arab Spring has roiled Libya and now Syria. The principle at stake in these violent conflicts has been termed the “Responsibility to Protect” (RTP). This language and the doctrine it names arose in contradistinction to the “Westphalian order,” the prevailing conception of world politics from the seventeenth century through the UN Charter, in which “order” meant protecting state sovereignty and ruling out military interventions by other states. While the UN Charter (1945) followed this logic, the UN Declaration of Human Rights (1948) argued that human-rights violations in any nation were the legitimate concern of other nations. The 1990s saw demands for precisely the kind of intervention the charter and international law had customarily forbidden. This debate shaped the concept of “Responsibility to Protect” and yielded a measure of support (never unanimous) for interventions in Bosnia, Somalia, and Kosovo. In a sense, the moral trumped the legal, creating a limited justification for intervention.

This is still a fragile norm in world politics, with fervent supporters and critics. American support can be decisive, and RTP deserves backing on moral, legal, and political grounds. But what kind of support? Domestically, both budgetary constraints and psychological exhaustion will place limits on any proposal for “boots on the ground”; internationally, after Iraq and Afghanistan, a U.S. lead role in any intervention may undercut RTP rather than advance it. President Obama was criticized by some for “leading from behind” on Libya, but his strategy recognized that, while the United States should be a player, it should not be the point of the lance on humanitarian intervention.

The third dimension of international politics is the transnational arena. The memory of 9/11 reminded us that an interdependent, globalized world order can be a fertile field for non-state actors committed to terrorist tactics and strategy. The Obama administration usefully put the “war on terror” rhetoric aside even as it continued the pursuit of Al Qaeda and Bin Laden. Defense against terrorism will remain part of any president’s global responsibilities; the key question will be how the responsibility is fulfilled. The strategic debates are endless, and reflect both continuity and change over the course of a decade and two administrations. The moral principle might be stated this way: In defense against terrorism and in pursuit of terrorists, don’t become a terrorist. The temptation to imitate the enemy is high in this kind of conflict. Moral principles that legitimate defense and pursuit are only as good as their ability to set limits and impose restraints, some of them absolute.

The very different agenda of “transnationality” moves the policy focus away from security and war to the issues of international economy, poverty and justice, climate and environment, and human rights. These issues constitute the challenge of globalization. John Paul II’s social teaching was wise and realistic about such questions. He recognized globalization as an abiding reality in world politics. But he believed it needed a moral framework to direct its impact on nations and individuals. For the United States, domestic budgetary constraints will operate in this arena, as will significant political and economic differences between our political parties, shaping different conceptions of how to address globalization. The world won’t go away, and even as the United States faces constraints on its economy, the agenda of world politics will continue to lay claim on us. May we welcome that claim and rise to its challenge.