As we enter uncertain times, who’s in charge in the US right now?

We’re in the midst of a strange and unnerving geopolitical vacuum right now.

Transitions between American presidencies are always fraught times.

Domestically, there’s always the question of how much the outgoing and incoming administration teams will cooperate.

Globally, White House transition is a time when countries align themselves as best they can to the new American administration.

It’s also a time they may want to manoeuvre, to get things done, to make moves, before the new occupant of the White House moves in.

At this time of profound global instability, and with a shift between two wholly different leaders with starkly different outlooks, this particular transition feels unprecedented and fraught with uncertainty.

Joe Biden is not just a lame duck president.

He is a very elderly man whose faculties, physical and mental, are a genuine cause for concern.

His fitness for office has been without sufficient US media scrutiny for far too long.

His appearance on the visit to Angola this week, where he had to be guided and helped around by his Angolan host, only served to underline the extraordinary fragility of the current American president.

As he was asked for updates on the developing situation in South Korea, which his own state department had described as “gravely concerning”, he could offer nothing except a confused look and a vague assurance that he was “being briefed”.

He absolutely does not present the attributes of the leader he needs to be at this time of global instability.

Then there is Donald Trump. His picks for his cabinet are undergoing impressive scrutiny which is exposing their suitability, and his judgement.

Beyond that spectacle, he is already making clear pronouncements with Trumpian gusto – on Ukraine, on Gaza, on tariffs and more – which are aspirational only until 20 January when he takes office.

He’s acting distinctly presidential already, comfortably filling the existing vacuum.

Mar-a-Lago has seen a flurry of world leaders visiting, all aware of how profoundly consequential his presidency could be.

This weekend, while President Biden is concluding a hugely belated trip to Africa that now feels like an “ought-to-do” afterthought, Mr Trump will be among world leaders in Paris at the reopening of the Notre-Dame Cathedral.

President Macron is fully aware of how much Europe now needs Mr Trump to be as close and aligned as possible.

Fears among many EU states that Russia is preparing for war with Europe within a matter of years are not overstated.

And so Mr Macron surpassed even himself with sharp, artful flattery by offering the Paris invitation to Mr Trump.

It will be Mr Trump’s presidential return to the world stage. A big moment, no question, and he will milk it.

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There have been numerous geopolitical moments in the past few weeks – developments in Syria, in Ukraine, in Gaza, in the West Bank, in Lebanon, in Georgia, on the Korean Peninsula.

In each of these places, and others, regional powers are manoeuvring to influence events and change facts on the ground ahead of 20 January.

We are in a uniquely vulnerable time right now and entering a particularly uncertain one.