Trump And The Limits Of International Restraint In Foreign Policy |
For decades after World War II, the international order rested on a simple promise: power would be restrained by rules.
The United Nations, international law, alliances and treaties were meant to act as guardrails. Not perfect guardrails. Plenty of wars happened anyway. Plenty of rules were bent. But the system worked on a kind of shared belief that even the powerful would at least pretend to follow the rules.
Since returning to the office in 2025, Donald Trump has eroded that belief. Examples include military strikes on Iran and Venezuela, talk of annexing Greenland, regular friction with European allies and a habit of brushing aside the United Nations when major diplomatic decisions are made.
Individually, each move can be explained away: security concerns, strategic competition and domestic politics. Put them together, and the picture looks different. It begins to feel as though the restraints built into the international system are no longer working as they were meant to.
Under the United Nations Charter, the use of force against another state is tightly restricted. In theory, military action is allowed only in self-defence or with authorisation from the United Nations Security Council.
Washington’s attacks on Iran and Venezuela do not fit neatly into either category, which would make them violations of international law. But here is the awkward part: international law does not enforce itself. Its authority depends heavily on whether states, particularly powerful ones, choose to respect it.
And when the most powerful military actor in the world decides otherwise, the tools available to compel compliance are limited. Diplomats understand this better than most.
Many governments concede that Washington has stretched long-standing norms. But their criticism tends to be cautious. Part of that caution is simple self-interest. The United States still sits at the centre of the global financial system. Its military reach is unmatched. Its influence runs through almost every major international institution.
If the system ultimately depends on the voluntary restraint of its strongest member, what happens when that restraint fades?
If the system ultimately depends on the voluntary restraint of its strongest member, what happens when that restraint fades?
Picking a direct fight with Washington carries risks: economic retaliation, sanctions, tariffs and diplomatic isolation. And tariffs, sanctions and trade pressure are tools that the Trump administration has shown no hesitation in using. The predictable result is restraint.
There are exceptions. A group of middle powers, including Canada, the United Kingdom and France, pushed back when Trump floated the idea of annexing Greenland. That resistance helped stall the proposal and raised the diplomatic costs.
But the same governments have been noticeably quieter when it comes to the strikes on Iran and Venezuela. Middle powers can slow things down. They can raise diplomatic costs. They can create friction. What they generally cannot do is veto the decisions of a superpower. The imbalance is simply too large.
China and Russia have condemned the attacks on Iran and Venezuela as violations of international law. But they have avoided steps that could escalate the confrontation directly. Meanwhile, India and several members of the BRICS grouping have largely kept their heads down. Strategic ambiguity beats open confrontation.
For now, much of the world seems content to watch, waiting to see how far Washington is prepared to go.
Inside the United States, the checks on presidential power have proven uncertain as well. The American system divides authority between the executive, Congress and the courts. In theory, that structure limits unilateral action. In practice, the guardrails have been uneven.
Congress has not mounted a sustained challenge to the administration’s overseas military operations. Political polarisation has made bipartisan resistance difficult. One institution has pushed back.
The U.S. Supreme Court recently blocked the administration’s attempt to use sweeping tariffs as a foreign policy weapon, ruling that the president had exceeded statutory limits. But courts rarely intervene in questions of war and military force. For decades, presidents of both parties have launched military operations without formal declarations from Congress.
Still, the biggest constraint on the administration’s strategy may not come from courts or treaties. It may come from economics.
Tensions with Iran have already rattled global energy markets. Oil prices surged after Iranian counter-moves and threats to shipping in the Strait of Hormuz, the narrow passage through which roughly a fifth of the world’s oil and liquefied natural gas travels.
To calm markets, the International Energy Agency released hundreds of millions of barrels from strategic reserves. It helped a little. But volatility remains.
Iranian officials have warned that prices could climb towards $200 per barrel if the confrontation deepens, a scenario that would ripple through the global economy. Energy shocks rarely stay contained. They show up in inflation, transport costs and grocery bills. Eventually, they land where politics is most sensitive: the wallets of voters.
This means the real constraint on presidential power may turn out to be political rather than legal.
For now, though, the international system faces a more immediate question. The rules that once promised to restrain global power still exist. The institutions meant to uphold them still function.
But their ability to enforce those rules against the world’s most powerful state looks uncertain. And that leaves governments around the world quietly wondering about something they rarely say aloud.
If the system ultimately depends on the voluntary restraint of its strongest member, what happens when that restraint fades?