Immigration must be regarded as a problem for Britain’s security, says the barrister Jonathan Hall, who advises the British government on counter-terrorism legislation, in the wake of the riots in Belfast following Monday’s knife attack there.

It is in an article in The Times on Wednesday that Hall analyses the significance of migration for national security and concludes that it must be relevant to public policy.

The British government adviser reminds readers that U.S. President Donald Trump has attempted to convey this message to European countries:

Last November, President Trump published his national security strategy, called “America First”, which made assertions about European countries, including our own, that have neither been addressed nor refuted.

One might argue that the document should be ignored because of its cultural-nationalist tone.

But I find it striking that such a close ally says that European migration policy is “transforming the continent and creating conflict”, and that these are matters relevant to America’s own national security. This raises the question: Is immigration relevant to ours?

Hall points to two situations in which immigration constitutes a security problem, first mentioning how hostile actors can exploit migration to send individuals abroad in order to cause harm.

He then highlights general immigration from violent regions:

Migrants from war-torn countries may well have participated in or been exposed to violence. Experience of trauma or exposure to violence is a factor when assessing the risk of future violence, and was recently added to the terrorism risk assessment tool (Kenyon et al., 2025) to reflect contemporary pathways to radicalisation. It may be associated with poor mental health, which is itself a risk factor.

This creates dilemmas, he continues:

A person who has been subjected to or participated in clan-based violence in a war-torn region may, for that very reason, have a strong claim to humanitarian protection. At the individual level, they may have a compelling moral claim and, under the law as it currently stands, also a legal entitlement.

But that person may also pose a risk that must be managed.

The ripple effects of violence committed by immigrants are likewise a security problem, he argues:

Even if there is no suggestion that it is terrorism-related, attacks such as Monday’s attack in North Belfast affect national security more broadly because they can trigger unrest, attacks on police and infrastructure, and shocking racially motivated violence.

The resulting destabilisation of social cohesion can be as damaging as terrorism, Hall concludes.

One cannot avoid engaging with this issue merely because Trump does so, he argues:

One might say that this is turning migration into a security issue. My point is that Trump has already done that. The question is: What do we say in response?