Keir Starmer will be walking a diplomatic tightrope when he meets Donald Trump on Thursday for the most significant meeting between a British prime minister and US president in decades.

The PM has been at pains not to directly criticise America’s commander-in-chief ever since he defeated Kamala Harris to secure a second term in the White House last November.

Nevertheless, it is indisputable that the two men do not see eye to eye on a wide range of issues, from Ukraine and Russia to the Middle East and global trade.

Starmer’s challenge during his 24 hours in Washington DC will be to stand up for his government’s strategic interests while strengthening the “special relationship” between the UK and the United States.

Here, HuffPost UK looks at the main challenges facing the prime minister as he walks the Trump tightrope.

Getting Agreement On Ukraine

On paper at least, this would appear to be the toughest conversation the two men will have.

Trump has spectacularly blown up the previous consensus among western leaders that Vladimir Putin was solely to blame for the war which has now been raging for three years.

Although the president’s desire for peace has been widely welcomed, his suggestion that Ukrainian president Volodymyr Zelenskyy is also culpable for the conflict, and then describing him as a “dictator” for not holding an election has provoked widespread condemnation.

While not attacking Trump directly, Starmer has made it very clear that he does not agree with his analysis.

At PMQs on Wednesday, the PM said: “President Zelenskyy is a democratically-elected leader and suspending elections is precisely what we did in this country when we were fighting in the Second World War.”

Starmer will have to draw on all of his powers of persuasion if he is to convince Trump that Putin is the true villain of the piece, and that any ceasefire agreement must come with a guarantee of US military support to ensure it is remains in place.

A senior No.10 source told HuffPost UK: “Stopping the fighting in Ukraine is not enough. It has to be a lasting peace - which needs US backup.”

Defence And The Future Of Nato

It is no coincidence that Starmer rushed out his announcement on Tuesday that the UK will start spending 2.5% of gross domestic product (GDP) on defence from 2027 - three years earlier than planned.

The PM wants to be able to go to the White House with tangible evidence of his government’s commitment to spending more on its military, just as Trump wants the whole of Europe to do.

Although the US defence secretary Pete Hegseth insisted a fortnight ago that America remains committed to the Nato alliance, he also stressed that his country would no longer provide Europe with the military protection it has enjoyed for the past 80 years.

With the threat from Russia growing, Starmer needs to persuade Trump not to completely turn his back on the Europe as he pursues his “America First” strategy.

The PM told MPs on Wednesday: “Nato is the bedrock of our security. It’s been our most important alliance for many, many years - as important today as it’s ever been. And we build that alliance by working with the US.” 

It’s The Global Economy, Stupid

Trump’s first month back in the Oval Office has not seen him resile from his campaign pledge to impose hefty tariffs on all imports into America.

Both Mexico and Canada - previously seen as close allies of the USA - were both given last-minute reprieves by the White House after the president announced swingeing levies on the goods they sell to his country. But the threat of a global trade war has not gone away.

The UK could also find itself in Trump’s crosshairs as his administration has also said it will impose tariffs on countries which impose sales taxes, like VAT.

Lord Mandelson, the UK’s newly-installed ambassador to Washington, has been working behind the scenes to ensure Britain gets a carve-out from the White House, and Starmer will need to follow that up with some winning arguments of his own.

The offer of a second state visit to the UK - including a sleepover at Balmoral Castle with King Charles - may well help to win over Trump, who is half-Scottish and known to be a huge admirer of the Royal Family. 

Chagos Islands Deal

When the government announced last October that it had reached an agreement to hand over sovereignty of the Chagos Islands to Mauritius, the White House could not have been more supportive.

Then President Joe Biden said: “I applaud the historic agreement and conclusion of the negotiations between the Republic of Mauritius and the United Kingdom on the status of the Chagos Archipelago.

“It is a clear demonstration that through diplomacy and partnership, countries can overcome long-standing historical challenges to reach peaceful and mutually beneficial outcomes.”

Under the deal, Britain will reportedly pay Mauritius £9 billion so that the UK-US military base at Diego Garcia will continue to operate as it does at the moment.

Trump’s re-election threw a giant spanner in the works, however.

Despite Starmer’s best efforts, the deal could not be ratified before Trump - who is known to be sceptical about the agreement because of its security implications - returned to the White House.

UK officials are still optimistic that the president will not veto the deal, but it is yet another tricky topic up for discussion in Washington tomorrow.

Oh Canada 

Possibly Trump’s most outlandish declaration - and there have been plenty of them - has been his desire to effectively annexe Canada and make it America’s 51st state.

The Financial Times has reported that senior advisers to Trump even want to remove Canada from the “Five Eyes” intelligence-sharing arrangement, which also includes the UK, Australia and New Zealand.

At PMQs, Tory MP Simon Hoare called on Starmer to make clear the UK’s opposition to his comments.

He said: “I hope the prime minister knows that when he does travel to Washington to meet the former leader of the free world, he does so with the hopes and prayers of this house and the country.

“While Ukraine will clearly dominate, will the prime minister undertake to raise with President Trump that Canada is a valued, respected and much-loved member of both Nato and our Commonwealth, and that this childish nonsense of a 51st state should be called out by the prime minister for what it is.”

Starmer replied: “The UK and Canada are close allies and have been for a very long time, with a partnership based on a shared history and a shared set of values, and a determination to be an active force for good in the world.

“We work closely with them on issues of the Commonwealth, on Nato and of course ‘Five Eyes’ intelligence sharing and we will work to strengthen that relationship.”

His comments will be welcomed by outgoing Canadian prime minister Justin Trudeau, but probably not by Donald Trump.