Steve Bannon, Donald Trump’s chief strategist and former editor of the Breitbart website, spoke at the Conservative Political Action Conference on Thursday.

One of his central arguments was that the Trump Presidency would deliver “an economic nationalist agenda”. But what does this mean? And should the rest of us be alarmed by its implications?

What is economic nationalism?

It seems to have emerged from Mr Bannon’s mind, rather than being any kind of concept used in political science or economics.

Mr Bannon talks about economic nationalism as the antithesis of “globalism”, which he characterises as a governing creed which has put the economic interests of multinational firms and a wealthy international elite above those of ordinary working class Americans.

Assuming that the term reflects the kind of political and economic policies Mr Trump has been espousing, it seems to be a cocktail of trade protectionism, hostility to immigration (especially Muslim immigration), political pressure on domestic corporations and belligerent unilateralism.

Does that mean tariffs then?

Mr Bannon certainly seems keen on the idea of imposing taxes on imports to the US and Mr Trump has made threats to impose large levies on the goods of Mexico to China.

In his inaugural speech in January the President asserted that: “Protection will lead to great prosperity and strength”.

In policy terms there is nothing much yet. Mr Trump has cancelled US participation in the Trans-Pacific Partnership, but this trade deal was not yet off the ground.

A Congressional tax plan under consideration by Mr Trump would involve a “border adjustment tax” on imports, but despite the name this would not really be a protectionist measure since the dollar would inevitably also rise cancelling out the competitiveness boosting effect.

The question is whether Mr Trump will ultimately follow through on his rhetoric and impose new tariffs on countries unilaterally, ignoring the rules of the World Trade Organisation (WTO) which forbid this.

If he does, what does it mean for the rest of the world?

Trouble. If the US does unilaterally impose tariffs other countries are likely to retaliate and the structure of the WTO could collapse.

Less trade would be the outcome, something every competent economist believes would lead to less prosperity.

This is especially dangerous for the UK as we seek to leave the EU and may need to rely on WTO rules if we cannot secure a free trade deal with the rest of the Continent.

The other major concern for other countries is that America could withdraw from its 70-year role in underwriting global security through Nato.

Mr Trump has called Nato “obsolete” and threatened to withdraw US protection unless other nations increase their expenditure contributions to mutual Western defence.

Does it mean higher government spending at home?

Unlike Republicans for the past thirty years, Mr Bannon seems keen on public infrastructure spending. Indeed, he sounds positively Keyensian in his ambitions.

“I’m the guy pushing a trillion-dollar infrastructure plan,” he says.

“With negative interest rates throughout the world, it’s the greatest opportunity to rebuild everything. Shipyards, ironworks, get them all jacked up. We’re just going to throw it up against the wall and see if it sticks.”

But there has been no infrastructure spending plan yet put forward. And the detail of a proposal put forward by two of Mr Trump’s other advisors last year proposed it should mainly take the form of tax cuts for firms, rather than direct government spending.

What about immigration?

Mr Bannon, when he hosted a radio show last year, made it clear that he blamed immigration for undermining American living standards, calling it “the beating heart of the problem”.

The ill-fated ban on travel from seven predominantly Muslim countries was reportedly railroaded through personally by Mr Bannon, who overruled the objections of Homeland Security officials.

A new ban, after the previous one was struck down by the US courts, is promised. And further moves designed to restrict immigration to the US may follow.

So is economic nationalism racist?

Unlike Mr Trump, Mr Bannon himself has not talked in explicitly racist terms and he claims he is not a “white nationalist”.

Yet Mr Bannon plainly has a “nativist” view of America.

He has talked contemptuously of globalism creating a “middle class in Asia”.

Mr Bannon also seems to be Islamophobic. In 2010 he ranted that “Islam is not a religion of peace” and wrote a fear-mongering film script.

Most damningly, Mr Bannon once proudly described Breitbart as the “platform for the alt right”. Alt Right essentially refers to the online white supremacist movement.

Mr Bannon is also openly sympathetic to other bigots, including the Le Pen family in France, who head up the Front National.

Is there anything else about Bannon we should know?

He has an apocalyptic mentality. Mr Bannon has reportedly talked of the West being “at war” with Islam.

One of his favourite books is reported to be The Fourth Turning, a theory that history unfolds in 100-year cycles, ending in cataclysmic change in which the old order is destroyed and replaced.