Shortly before Christmas in 1984, Margaret Thatcher famously declared her liking of Mikhail Gorbachev, insisting “we can do business together”. Just three months after their historic London meeting, “the great reformer” became leader of the Soviet Union.

Together with the US’s then-president Ronald Reagan, the three plotted the ending of the Cold War. By the end of the decade, the Berlin Wall and the Iron Curtain had fallen, Europe was being dramatically reshaped as the USSR dissolved and modern Ukraine emerged from the geopolitical maelstrom. Roll forward 40 years from that historic meeting and Sir Keir Starmer finds himself in a strangely similar, albeit far more complex, position.

Like the Iron Lady, the current Prime Minister is having to do “business” with a president to bring about global peace.

But rather than the Russian leader, it’s the supposed leader of the Free World who Sir Keir is negotiating with.

Donald Trump’s “shock and awe” start to his presidency, coupled with his allegiance with Vladimir Putin, ripped up the rule book and left the world order, in place since 1945, teetering on the brink.

As well as trying to broker peace in Ukraine, the PM, along with French president Emmanuel Macron, is having to act as a transatlantic bridge to shore up America’s long-term commitment to European security.

The future of NATO as we know it is in jeopardy and we now have the previously unthinkable situation of America siding with Russia and North Korea at the United Nations vote on ending the Ukrainian conflict.

The saloon bar diplomacy of last week’s infamous White House bust-up between Mr Trump, his vice-president JD Vance and Volodymyr Zelensky was indicative of how the tectonic plates are shifting.

So how did we reach this point and what happens next?

Following his stunning US election comeback victory, few would have been surprised that Mr Trump was intent on shaking things up during his second crack at the presidency.

The Republican strongman eventually rumbled into 1600 Pennsylvania Avenue, Washington DC, during a January deep freeze, immediately signing a blizzard of executive orders that signalled he meant business.

But it was his unexpected call with Putin on February 12 which really sent shockwaves around the world as he offered the Kremlin tyrant a way back in from the cold.

Putin’s decision to launch a full-scale invasion of Ukraine in 2022 had turned him into a pariah, with the UN overwhelmingly adopting a resolution condemning Russia for its “unlawful use of force against Ukraine.”

Russia was hit by thousands of international sanctions.

The following year, the International Criminal Court issued an arrest warrant for the Kremlin leader.

As for the president of the United States – then Joe Biden – he left no doubt of what he thought of his Russian counterpart, condemning Putin as a “murderous dictator” and a “pure thug”.

There were no more telephone calls between Putin and Mr Biden.

Fast forward to 2025 and “that” call.

Mr Trump said he wants to “work together, very closely” with Putin to end the war in Ukraine. He hopes they will be “visiting each other’s nations”.

Clearly, so does Putin, who invited Mr Trump to Moscow.

If that visit goes ahead, it will signify a major shift in US-Russian relations.

An American president has not visited Russia for more than a decade.

In many ways, Putin has already got what he wants – the chance to negotiate directly with the United States on Ukraine as well as the opportunity to put himself at the top table of international politics.

It remains unclear, though, how far Putin will be willing to compromise.

Russian officials claim Moscow is ready for talks but always refer back to Putin’s so-called peace proposal of June 2024.

Under that plan, Russia would get to keep all the Ukrainian territory it has seized, plus some more land still under Ukrainian control.

On top of that, Ukraine would not be allowed to join NATO and Western sanctions against Russia would be scrapped.

Central to all of this is the rollercoaster relationship between the US president and Mr Zelensky.