On 5 September 2025, to convey 'a stronger message of readiness and resolve', US President Donald Trump signed an executive order changing the name of the Defense Department to the Department of War. This change in the lexicon matters, because it comes from the government of the world's most powerful military force; one that wields a nuclear arsenal capable of ending life on Earth as we know it. Words matter — all the more when their meanings begin to shift.

Analysis has long shown that such shifts may signal attempts by politicians to influence public discourse to further their own agendas. Over the past year, politicians' definition of deterrence has begun to change — and that should be reason to pay attention.

The term deterrence has never belonged exclusively to the nuclear realm. A look at US policy debates over recent decades offers numerous examples of policymakers discussing deterrent effects in a variety of contexts. These include the deterrent effect of the death penalty, or strategies to deter Russia from interfering in US elections.

Nevertheless, for over seven decades, the word deterrence has been used primarily in the realm of nuclear discourse. That association, however, began to unravel under the second Trump administration.

The discursive shift of deterrence

In the first year of Trump 2.0, the term deterrence underwent two substantial changes. Politicians began to apply it across an increasingly broad range of issue areas. The word also took on a more proactive and aggressive meaning.

Members of the Trump administration frequently used the term at the domestic level. They justified sending the National Guard to US cities as 'deterrence'. Trump's government also made it a priority to deter illegal migration — through excessive aggression of ICE agents, for example.

The definition of 'deterrence' has undergone substantial changes under Trump, taking on a more proactive, aggressive meaning

At international level, the US government used the term even more expansively. Attacking Venezuelan ships and killing their passengers was 'deterring drug smuggling', which turned out to be a prelude to military regime change. Bombing Iranian military facilities was a way to 'reestablish deterrence'. Republicans supported this, and a Senate resolution even suggested Trump 'worthy of consideration for the Nobel Peace Prize'. Military innovation was strengthening deterrence. Tellingly, in its 2025 Review, the US Department of War presented these and other issue areas under the heading 'Reestablishing Deterrence'.

Deterrence: a history

The history of the term deterrence might reveal the reasons for this discursive shift. With the advent of nuclear weapons, deterrence rose to prominence and became closely associated with nuclear discourse. During the Cold War, US politicians often touted deterrence as a peaceful means to protect the so-called West from the Soviet threat. Deterrence, they claimed, was a peaceful way of safeguarding the free world from the 'evil empire'. Nuclear deterrence could stabilise the international order and avoid the need to transform it into a garrison state.

During the Cold War, 'nuclear deterrence' was seen as a means to protect the West from the Soviet threat, and stabilise the international order

When we compare the Cold War’s reactive, protective portrayal with the Trump administration’s proactive and aggressive usage, deterrence's increasingly aggressive nature becomes clear. Bombing ships and military facilities in Venezuela and Iran is a quite different kind of deterrence from threatening force to deter imminent military aggressions. Neither does deploying the national guard in response to dubious claims about opposition-led states fall under the previously understood notion of deterrence. The current US government is using the seemingly peaceful term to conceal its increasingly aggressive military posture and renewed interventionism — globally and domestically. And this is where the danger lies.

The nuclear consequences of the deterrence shift

Expansion of the term deterrence into an umbrella concept risks triggering another, potentially even more dangerous, side effect. Deterrence could become a catch-all term for military intervention. Small-yield nuclear weapons are under development. There are discussions around their potential deployment, and the rejection of a No First Use policy. There is a growing risk that these tactical nuclear weapons could be employed early in a conflict to 're-establish' deterrence against other states.

The Trump administration has already presented the bombing of Iran and Venezuela as deterrence. In the future, it may thus justify the pre-emptive use of tactical nuclear weapons under the same logic. Trump’s October 2025 announcement that his government intended to resume nuclear weapons testing 'because of other countries' nuclear testing programs' may well be a first step in that direction.

'Deterrence' now risks becoming merely a catch-all term for military intervention

At the doctrinal level, this may lead to a position similar to the alleged Russian doctrine of 'escalate to de-escalate'; using a tactical nuclear weapon early in a conflict to deter opponents from further engagement. In other words, to re-establish deterrence. While deployment of nuclear weapons may not currently be topmost in US policymakers' minds, some of Trump’s statements have raised the stakes. In May 2025, Trump announced his project to build a 'Golden Dome' missile defence system. In December, he unveiled plans for a new class of battleship equipped with nuclear cruise missiles.

How 'deterrence' is legitimising nuclear weapons

The developments outlined above may represent a disguised erosion of the nuclear taboo — one that enters through the back door. By implicitly legitimising nuclear weapons through the continued use of their closely linked term, deterrence, a broader and more aggressive interpretation could mark the beginning of public and political acceptance of their potential use. If deterrence comes to encompass aggressive, pre-emptive military actions, it could enable an increasingly militarised interventionism — domestically and abroad — under the guise of peaceful protection. It may also foster a growing willingness to consider, and legitimise, the use of nuclear weapons to re-establish deterrence against nuclear competitors.

Is the nuclear umbrella being refashioned into a sword?

☢️ No.33 in a series on the Nuclear Politics Paradox

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