By William Sweeney
In January 2026, President of the United States Donald Trump threatened to acquire Greenland ‘the easy way or the hard way‘. The previous year, he described US allies as ‘free riders’ and doubted whether the United States would defend them if they did not spend enough on their militaries. Over the past year, the President has shown an unprecedented willingness to use military force – at the expense of allies – to achieve what he wants, as seen in Venezuela and Iran.
These instances of erratic behavior by a NATO member have raised alarm bells from London to Taipei, as the United States seems increasingly willing to turn its back on longtime allies for seemingly puzzling or contradictory reasons. Trump threatened his allies over Greenland on national security grounds, yet the United States already had a treaty allowing it to deploy and operate military facilities on the island under the 1951 Greenland Defense Agreement. The dispute has since moved beyond threats: on September 22, 2026, the United States, Denmark, and Greenland signed a new security agreement that expands the American military presence while reaffirming Greenland’s status within the Kingdom of Denmark. The agreement may strengthen Arctic security, but it does not erase the damage Washington’s earlier threats to an ally’s territorial integrity caused.
The Iran conflict has produced a similar tension. Trump berated allies for not helping to open the Strait of Hormuz and raised the possibility of the United States withdrawing from NATO. European allies were reportedly not consulted before the operations began. Following the recent midterm elections, Trump described the war as militarily ‘effectively over’, even as a naval blockade and difficult negotiations continued. Whether that is true remains an open question, but the episode has already raised questions about American leadership.
Moreover, the Trump administration has withdrawn from the WHO and the Paris Climate Accord. It has also cut billions in foreign aid spending and tried to impose sweeping tariffs on almost every nation. What we are seeing is easily attributed to a leader who is a ‘loose cannon’, someone without any coherent strategy. While that may be true, Trump’s erratic diplomacy reflects something deeper: a post-Cold War America without a bipartisan foreign policy foundation. Trump is the President and, as such, wields enormous power, but sustained pushback within his own caucus has been limited. Besides the occasional dissenting voice, the Republican Party seems to be publicly content with the freewheeling brashness of Trump’s doctrine.
The Democrats, on the other hand, detest what they see as a chaotic and rogue administration floundering on the international stage. Democratic Senator Chris Murphy described the administration as ‘completely, utterly unhinged‘ in reference to Trump’s profanity-laden post in early April. When Joe Biden took office in January 2021 after Trump’s first term, he took many steps to reverse his predecessor’s foreign policy. For example, Biden rejoined the Paris Climate Accord, worked to restore NATO alliances (including spearheading the effort to arm Ukraine), and revoked travel bans targeted at some Muslim-majority countries. Trump has since reversed or weakened many of these efforts in his second term. The pattern, by now, should be familiar. And it is likely to be repeated.
The 2026 midterm elections add another dimension to this problem. Republicans’ losses gave Democrats control of Congress, allowing them to scrutinize Trump’s agenda through oversight. Yet Congress’s ability to constrain the President’s foreign policy and military actions remains limited. A change in congressional control may alter the political costs of Trump’s decisions, but it does not guarantee a change in strategy. The tension between presidential power and domestic opposition is therefore likely to persist.
For the sake of argument, say that a Democrat wins the presidency in 2028. They start to undo the ‘Donroe Doctrine‘ and are open to repairing US relationships with the United Nations and NATO, like Biden in 2021. How is the world going to react? Will NATO suddenly become comfortable with the US as an ally again? How will China react to an administration more likely to support Taiwan? Even when working toward reconciliation, the world will wonder how long it will last. They will wonder if another change in the presidency will usher in a new era of uncertainty. In this sense, the United States’ foreign policy is shaped by election cycles rather than a durable strategic vision.
‘Politics stops at the water’s edge’ was coined by Senator Arthur Vandenberg when he voiced his support for Harry Truman’s internationalist policies during the Cold War. Vandenberg’s principle held true for most of the Cold War. Yes, toward the end of the Vietnam War, there was growing opposition to the war, especially during the 1968 election. However, the Soviet Union remained a shared enemy, and Americans shared goals for defeating it. John Lewis Gaddis noted that Containment became a “remarkably durable consensus” across administrations. The Soviet Union unified American foreign policy more than any doctrine or diplomat ever could.
When the Soviet Union fell in 1991, the organizing principle of American global leadership collapsed with it. For a while, international law and the creation of a liberal world order seemed to replace it, but that never fully materialized. The seemingly ‘rules-based’ order that had existed for 30 years has been under sustained strain over the past decade. Isolationist and reactionary movements skeptical of US intervention have clashed with the ‘establishment’ –a catch-all term for those preferring a more assertive US foreign policy. Each party now has a sizable isolationist contingent.
But this raises a deeper question than who is to blame. It asks something more uncomfortable about the nature of hegemonic foreign policy itself: was the Cold War consensus ever about bipartisan values, or was it always about a common enemy? The Roman Empire was not held together by agreement on governance; it held together because expansion gave it a common purpose. Athens united the Greek world against the Persian threat, but that alliance frayed once the threat was beaten. The Mongol Empire, like Rome, fragmented once conquest ceased to be the organizing logic. While the United States’ foreign policy consensus may not have been motivated by conquests like those of empires of old, the Soviet Union served as a similar motivator. Great powers, it seems, have rarely held together around what they stand for. They cohere around what they stand against.
In a democracy, this is even more pronounced. Every foreign policy decision becomes politicized. Remember the outrage from Republicans over Biden’s withdrawal from Afghanistan? Or the uproar from Democrats over Trump’s war with Iran? There is no single ‘bad guy’ to justify US policy, only the broad title of ‘national security interests’ –interests, I may add, that change from administration to administration. For instance, sending money and weapons to Ukraine seems to have fallen out of that priority in Washington. European allies and Canada now finance the vast majority of security assistance to Ukraine, with NATO’s July 2026 declaration pledging €70 billion in military equipment, assistance, and training for Ukraine during the year. This is not to say that support for Ukraine has disappeared, but that responsibility for it has shifted, reinforcing the question of whether American commitments can survive a change in political priorities. NATO’s declaration makes that shift explicit.
It would not be wrong to point to the Taliban or ISIS post-9/11 and argue that the Global War on Terror that followed produced a common enemy for the United States. For a brief window, it did. But consider what kind of enemy. The Soviet Union had a capital, a border, a nuclear arsenal, and a rival ideology. You could contain it, negotiate with it, and ultimately outlast it. The Taliban and ISIS offered none of that. An enemy defined by tactics rather than territory cannot be defeated in any conventional sense, and the post-9/11 consensus could not be sustained. Sure enough, what began as a unified front splintered and collapsed into debates over torture, government surveillance, and presidential military powers. International alliances began to fracture as well. The UN was routinely bypassed, and both France and Germany refused to follow the United States into Iraq. The War on Terror did not replace the Cold War consensus. If anything, it demonstrated how badly America needed one.
China presents a compelling long-term candidate. It is an authoritarian great power with explicit global ambitions and a rival vision of world order that challenges the liberal international system. Yet China resists functioning as a pure organizing enemy—at least for the time being—for the United States to rally around. The United States and China trade hundreds of billions of dollars annually. American supply chains, consumer goods, and financial markets are structurally entangled so that China may be a competitor with the United States, yet could never be treated as an ‘enemy’ in the same way as the Soviet Union. This is despite what US politicians may claim. Recent US-China trade talks have also shown that rivalry does not preclude negotiation: in November, the two governments announced a pathway toward reducing some of the trade and export-control measures imposed on one another. China may be a viable candidate for an organizing enemy. The conditions, however, that would make that enemy functional as a consensus-builder do not—at least not yet.
So, where does this leave American foreign policy going forward, beyond Trump? The United States finds itself in a peculiar position for a hegemon: internationally powerful, but rudderless. America is left to either find a new organizing principle for its foreign policy or keep oscillating between administrations—and the rest of the world will not wait to find out which. Allies are already hedging. European governments are increasing defense spending and debating how much of their continent’s security they can provide without Washington. NATO’s own direction increasingly emphasizes greater European responsibility, even as European militaries remain dependent on key American capabilities.
But we are left with an even more uncomfortable truth. A liberal democratic superpower without consensus is left as a loose cannon, swinging back and forth. International strategy is increasingly guided by the whims of party politics. Coherence is lost, and thereby the United States’ status in the world changes. Allies become distrustful, and competitors see opportunities. This raises a question that cuts deeper than any single presidency. Can a liberal democracy sustain the kind of coherent, durable foreign policy that great-power status demands — without an enemy to rally around? Can a democracy stem the tide of history and sustain foreign policy beyond competition? The history of empires suggests the problem is older and harder than any institutional fix. Athens never figured out a solution. The United States, importantly, is not Athens, but it is still asking the same question Athens never had time to answer.