THE Yes movement is well used to dealing with slander.

To a certain extent, the lobbing of puerile insults at opponents is a predictable result of a UK political culture influenced by the rambunctious, private-school atmosphere of Westminster.

But in recent years it feels as though hostility towards pro-independence politics has increased in severity.

Political cartoons published in national newspapers depict pro-independence politicians being beheaded or hanged.

The UK Government proudly refuses to fund artists who don’t support the Union.

And, now, the Prime Minister himself feels it is appropriate to mention “Scottish nationalists” in a speech on extremist threats facing the UK.

READ MORE: Scottish Tory MSP squirms amid challenge on 'extremism' comments

On Monday, Rishi Sunak suggested that pro-independence supporters represent a threat to the security of the UK in a similar manner to Russia, North Korea and Iran.

According to Dr Alan Greene, a reader in constitutional law and human rights at the University of Birmingham, the inclusion of an entirely legitimate and democratic political movement among the ranks of terrorists speaks to the increasing desperation of this Tory government.

“It’s par for the course for this government to conflate anything outside their own narrow understanding of the world with extremism,” he said.

“It’s obviously absurd to equate Scottish nationalism with a state superpower like Russia.”

But Greene notes that this kind of rhetoric can’t be shrugged off like a barbed comment at PMQs. It can have real and violent consequences.

The National: Rishi Sunak

“It’s interesting to me that Northern Ireland was left entirely out of that speech,” added Greene.

“But that’s precisely because the Prime Minister knows it’s a sensitive issue and that using that kind of rhetoric in the context of Northern Ireland is fundamentally dangerous – particularly when he’s doing it for entirely political reasons”.

Mercifully, Scotland doesn’t have the same history of violence surrounding the political debate on the constitution.

The Yes movement is far more likely to be caught painting stones than throwing them.

But in a country where politicians of all stripes are forced to fear for their security, it doesn’t make it any less irresponsible.

What is an 'extremist'?

In March, the UK Government issued a new definition of extremism as “the promotion or advancement of an ideology based on violence, hatred or intolerance”.

It explicitly states that the definition “is not intended to capture political parties that aim to alter the UK’s constitutional makeup through democratic means”.

Evidently, this appears to contradict the Prime Minister’s speech.

Yet as Greene points out, the nature of the UK’s counter-terrorism apparatus means that nationalists could still fall foul of Prevent – a UK Government strategy that aims to stop people becoming involved in terrorism.

“The definition isn’t enshrined in law,” he said.

“It’s just government guidance. The vagueness of the definition would make putting it on the statute an absolute nightmare because it’s so broad.

READ MORE: Police threaten National journalist with arrest at arms protest

“But because of how Prevent works – with people who are not fully trained tasked with the responsibility of stopping people being drawn into terrorism – the Government can still use rhetoric to influence their actions.

“It’s doctors, teachers and nurses who are on the front lines of counter terrorism for Prevent.

“Allowing extremism to be defined so broadly in the public sphere leads the way to discriminatory applications of counter terrorism.”

This concern becomes particularly acute when you look at how terrorism and extremism are used in political discourse in the UK.

Recep Onursal, an assistant lecturer in politics and international relations at the University of Kent, co-authored a study looking at the convergence of “extremism” and “terrorism” in British parliamentary discourse.

He found that the terms were increasingly being used interchangeably, with “discourse on terrorism now encompassing both violent and non-violent forms of extremism”.

The National: Campaigners wave Scottish Saltires at a 'Yes' campaign rally in Glasgow, Scotland September 17, 2014.

“This shift indicates that counter-terrorism strategies no longer focus solely on behaviours that directly support political violence but have expanded to include ideologies that do not conform to state-defined norms,” he told the Sunday National.

“Practices previously associated with ‘terrorism’ are now being applied to those labelled as extremist.

“However, targeting non-violent extremism as if it were terrorism is problematic because it closes off possible opportunities for dialogue essential for conflict transformation.

“This approach could treat any deviation from mainstream norms as akin to terrorism, leading to an environment that restrictively narrows the scope of acceptable political dialogue.

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“In this sense, Rishi Sunak’s recent inclusion of Scottish nationalists in a list of extremist threats exemplifies the concerning trend highlighted in our research.

“It improperly conflates legitimate political dissent with genuine security risks, thereby undermining the very liberal democratic values and democratic rights that Mr Sunak purports to uphold.

“Democratic politics are inherently conflictual, but this conflict should not be seen as something to eliminate.

“Instead, it is a vital aspect of democracy, allowing for continuous engagement and contestation among different ideological positions within a framework of mutual respect.”

'It's laughable' 

There is no intellectually coherent reason to treat pro-independence campaigners as extremists.

Yet the constant lowering of the bar of political debate in the UK Parliament has led us to the point where the people who organised a mass linking of arms across Scotland are considered within some ranks of the Conservative Party to be enemies of the state.

“It’s pretty horrible that those of us campaigning for an independent Scotland through democratic means are being lumped by Rishi Sunak into a similar category as terrorists and rogue states,” said Gareth Morgan, the secretary of Yes Dunbar.

“In the past, I thought Rishi Sunak had supported the notion of the UK as a voluntary union of nations.

“But it now appears that that Mr Sunak no longer supports the democratic rights of the Scottish people to decide on the matter.

READ MORE: John Swinney says Alister Jack kept Scots nuclear plans secret

“Maybe these remarks will win him a few more hardline Tory votes in Scotland but I think many moderate voters will be horrified, right across the UK.”

Morag Williamson of Yes for EU argued that the toxic nature of Sunak’s speech only highlights the need for independence.

“It’s laughable,” she said.

“And it's ironic given his own government’s creeping authoritarianism.

“But Sunak’s comments are also dangerous: he is making a cynical attempt to stoke fear and hate.

"He ignores the fact that about half the Scots population want independence, and have consistently for many years elected pro-independence majorities to the UK and Scottish parliaments, as well as local authorities.

“It is politically – and mathematically – illiterate to claim that the majority are ‘extremists’.

“Scots have a rather better understanding of democracy than the UK PM. His cynical ploy will be ultimately ineffective or will backfire on him.

“He is showing just how toxic the UK Government is and how important it is that we achieve our independence, asap."

In a country where the Prime Minister allows his own political desperation to overtake his government’s commitment to democratic norms, it’s no surprise that support for independence remains strong.

With each passing day and each incremental escalation of authoritarian rhetoric, it’s easy to see why many feel it is more necessary than ever.