How far can they project military force?
How quickly can they respond to a threat?
How sophisticated are their weapons?
How effectively can they defend themselves and their allies?
These questions matter.
But there is another question that matters even more:
What happens after power has been used?
The continuing war with Iran is becoming a test not simply of military capability, but of strategic judgement.
The United States remains extraordinarily powerful. Its technological advantages, global military presence, intelligence capabilities and capacity to conduct complex operations across enormous distances remain formidable.
Yet military superiority does not remove strategic limits.
Sometimes it reveals them.
Winning battles is not enough
Modern history repeatedly demonstrates that the ability to defeat an adversary militarily does not guarantee the ability to create the political outcome that was originally intended.
Targets can be destroyed.
Military infrastructure can be degraded.
Command systems can be disrupted.
An adversary can be weakened.
None of this necessarily answers the question of what comes next.
The distinction between military achievement and political success becomes increasingly important as a conflict continues.
A short operation may be judged according to relatively clear objectives. A prolonged war is different. Each additional month brings new costs, new risks and new possibilities for escalation.
Objectives can also change.
A war that begins with one purpose may gradually acquire others. Preventing a particular threat can become weakening a regime. Weakening a regime can become changing its behaviour. Changing behaviour can gradually become an expectation of political transformation.
At some point, means and ends can become difficult to distinguish.
That is where strategy matters most.
Power is finite
There is a persistent assumption that the resources of a great power are effectively unlimited.
They are not.
Modern warfare consumes highly sophisticated weapons at extraordinary rates. Defensive interceptors, long-range missiles and other advanced systems can be used in seconds but require substantial time, industrial capacity and money to replace.
This creates a basic strategic problem.
Every weapon used in one theatre is a weapon unavailable somewhere else.
Every military system moved to reinforce one region changes the balance of readiness in another.
A global power therefore cannot assess a war only by asking whether it has sufficient resources to continue that particular conflict.
It must preserve sufficient capacity for conflicts that have not yet begun.
That distinction is fundamental.
Strategy is partly the management of uncertainty.
No government knows where the next crisis will emerge. No military planner knows which deterrent will suddenly become essential. No alliance system can assume that only one region will demand attention at a time.
The stronger a country becomes globally, the more widely distributed its responsibilities become.
Power creates commitments.
Commitments consume power.
The economics of exhaustion
There is another uncomfortable reality.
Technological superiority can be extremely expensive to maintain against relatively inexpensive threats.
A sophisticated defensive missile may be required to destroy a much cheaper attacking weapon. A drone costing comparatively little can force an opponent to activate systems worth many times more.
If this happens repeatedly, the question is no longer simply whether each attack can be defeated.
It becomes whether the exchange itself is sustainable.
War therefore remains an economic contest even at the highest levels of technology.
Industrial capacity matters.
Supply chains matter.
Production time matters.
And patience matters.
An adversary does not necessarily need to defeat a stronger military directly if it can impose costs over a sufficiently long period.
This is one reason wars of attrition are so dangerous.
Both sides may continue because each believes that the other will reach its breaking point first.
Sometimes neither does.
Instead, both become weaker.
Deterrence depends on what remains unused
Military power has an unusual characteristic.
Part of its value comes precisely from not using it.
A missile sitting in reserve can deter an adversary.
Once fired, it can destroy a target, but it can no longer deter another adversary somewhere else.
This creates a paradox at the centre of military power.
Force may need to be used to demonstrate credibility.
But excessive use of force can gradually reduce the capabilities upon which credibility depends.
Other governments watch this carefully.
They observe which weapons are being consumed, which military assets are being redeployed and which regions are receiving less attention.
They study not only victories and defeats but exhaustion.
A prolonged war therefore communicates information far beyond the battlefield.
Potential adversaries are watching.
So are allies.
Alliances are also power
Military inventories are not the only resources that can be depleted.
Trust can be depleted too.
A great power’s influence is multiplied by allies that believe its commitments are credible, its judgement is reasonably predictable and their interests will be taken seriously.
Such relationships are strategic assets.
They cannot be manufactured quickly.
If partners begin to doubt whether a powerful ally can protect them, or whether its decisions may expose them to risks they did not choose, they will naturally reconsider their options.
Some will seek greater independence.
Some will diversify their relationships.
Others may remain formally aligned while becoming strategically more cautious.
None of this necessarily produces a dramatic rupture.
International influence often declines quietly.
A treaty remains.
A military base remains.
Diplomatic language remains friendly.
But confidence becomes thinner.
And eventually that matters.
Survival is not victory
The same caution should apply in judging Iran.
The ability to endure does not mean that a country is winning.
Military losses, economic pressure, damaged infrastructure, reduced trade and prolonged uncertainty impose enormous costs on a society.
A government may survive all of these.
Survival itself may even become part of its political narrative.
But survival and strategic success are not identical.
This is one of the traps of prolonged conflict.
The stronger side can point to the damage it has inflicted.
The weaker side can point to the fact that it still exists.
Both can therefore construct a story of success.
Meanwhile, the costs continue accumulating.
The hardest question
Eventually every war confronts political leaders with a question that military power cannot answer:
What outcome is sufficient?
Not perfect.
Not total.
Sufficient.
This may be the most difficult word in strategy.
Political leaders understandably prefer decisive outcomes. They want threats eliminated, adversaries defeated and objectives fully achieved.
Reality is rarely so accommodating.
Sometimes the choice is not between victory and defeat.
It is between an imperfect settlement today and a potentially worse situation tomorrow.
Recognising that point is not weakness.
It is judgement.
Diplomacy is part of power
Diplomacy is sometimes described as what happens after military options have failed.
That misunderstands both diplomacy and power.
Military force can change calculations.
Diplomacy can translate those changed calculations into arrangements that endure.
One without the other is often incomplete.
The purpose of applying pressure should therefore not simply be to demonstrate that greater pressure remains available.
It should be to create conditions in which political agreement becomes preferable to continued conflict.
That requires something more difficult than escalation.
It requires understanding what the other side needs in order to stop.
Not because its demands must be accepted.
Not because its actions should be excused.
But because wars normally end through decisions made by adversaries, not merely through damage inflicted upon them.
The responsibility of strength
There is a deeper lesson here.
We often associate power with freedom of action.
The more powerful a state is, the more choices it possesses.
But genuine power also creates responsibility for restraint.
A weaker actor may have few alternatives.
A stronger actor usually has more.
That makes the quality of its judgement more important.
The ultimate test of power is therefore not whether it can be exercised.
It is whether those who possess it can distinguish between what is possible, what is necessary and what is wise.
The war with Iran will eventually end.
We cannot yet know the settlement, the costs or the longer-term consequences.
But the questions it raises extend far beyond one conflict.
How much military power is enough?
How much should be kept in reserve?
What obligations does a government have to allies affected by its decisions?
At what point does persistence become exhaustion?
And how does a country recognise that moment before its adversaries do?
Great powers rarely cease to be great because they suddenly lose all their strength.
More often, their difficulties begin when commitments expand faster than resources, military action becomes easier than political resolution, and confidence in power obscures the need to preserve it.
Strength therefore requires something that can appear, superficially, to be its opposite.
Restraint.
Because the highest expression of power may not be the ability to continue indefinitely.
It may be knowing the point at which continuing no longer serves the purpose for which power was used.
- Jamie Webb contributes to Agora Dialogue on questions of power, public responsibility and democratic accountability, with a particular interest in the ethical and political choices that shape contemporary societies.