Should we be worried about a Donald Trump presidency?

A man described by not one but two of his closest former aides as a fascist will become the most powerful man in the world when he takes office. How worried should we be?

Very, say another dozen White House staffers who served under Donald Trump and watched him in action for his first four years in power.

In a second term, they are warning that those who once tried to prevent him from acting on his worst impulses will no longer be there to rein him in.

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“The grown ups”, as they were called in Mr Trump’s first administration, will have gone, replaced by people more aligned with his agenda and pushing their own.

What is that agenda and what is to come? That is harder to say. We have learned not to take Donald J Trump literally – his empty promises, lies, and false threats come thick and fast.

The first time round, many of his promises came to nothing; to build a border wall and have Mexico pay for it, to bring peace to the Middle East, to end North Korea’s nuclear weapons programme, and Iran’s too.

But we can say what is likely; trade wars with China, Mexico, and Canada seem probable.

The extent of the tariffs Mr Trump imposes are harder to predict but the impact on the global economy will most likely be considerable.

He could rip up more treaties the US has signed, including climate commitments made by his predecessors.

Mr Trump is likely to undo much of the Biden administration’s work to reverse climate change and the negative impact on the planet may be substantial.

And he is likely to negotiate an end to the Ukraine war largely on Moscow’s terms if his words and those of his team are anything to go by.

His running mate JD Vance says Russia will keep the land it has taken and receive a guarantee of Ukrainian neutrality. Putin could not have hoped for more.

Those hoping for an end to the war in Gaza may be disappointed too.

Donald Trump and Israeli Prime Minister Benjamin Netanyahu are close allies.

He is likely to give the Israelis plenty of latitude when it comes to the conflict. And there are fears he would not restrain Israel in any future confrontations with Iran unlike the Biden administration, with all the risks of a wider Middle Eastern war that might ensue.

NATO’s uncertain future

Trump’s impact on NATO is harder to predict. His team has floated various plans for the alliance. They all arguably weaken America’s support for it.

Without America’s cast-iron guarantee, will other countries seek their own security arrangements? It seems likely.

One of the great pillars of the post-world war order will have been weakened. But Mr Trump in his first term showed contempt for all its multi-lateral, multinational organisations.

America swings through cycles of isolationism, retreating from the world, then having to re-engage at huge cost to protect its interests.

Mr Trump may prove unwilling to learn the lessons of that history.

Those who regard America, for all its faults, as a positive influence in the world, an example to follow, will be most worried and disheartened.

A demagogic populist, regarded as a fascist by some of those who know him best and who openly admires authoritarians and dictators, will be taking up the reins of power again in the world’s most powerful democracy.

Half of American voters have opted for a man who refused to accept election defeat four years ago, used lies and dirty tricks to try and undermine its result, and stood by while an angry mob ransacked the citadel of American government.

All of that will only embolden other strongmen the world over and damage, perhaps beyond repair, the democracy that Americans have long believed stands as an example for all the world to follow.