The warning and surge in US military presence comes almost two weeks after Donald Trump urged Iranian protesters - thousands of whom have been killed by the regime's forces - to keep demonstrating and promised that "help is on the way".

"This military ‌build-up - we hope it is ‌not intended for real confrontation - but our military is ready for the worst-case scenario. This is ‍why everything is on high alert in Iran," said the Iranian official, speaking ‌to Reuters on condition of ⁠anonymity.

The official went on to say: "This time we will ‌treat any attack - ‍limited, unlimited, surgical, kinetic, whatever they call it - as an all-out war against us, and we will respond in the hardest way possible to settle this."

President Trump said on Thursday that the US had an "armada" heading toward Iran but hoped he would not have to use it, as ‍he renewed warnings to Tehran against killing protesters or restarting its nuclear programme.

"If the Americans violate Iran's sovereignty and territorial integrity, we will respond," said the Iranian official.

He declined to specify ‌what an Iranian response might look like.

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The US military has in the past periodically sent increased forces to the Middle East at times of heightened tensions, moves that were often seen as defensive.

However, the US military staged a major build-up last year ahead of its launching airstrikes against Iran's ‍nuclear programme in June.

Another build-up was seen in the Caribbean towards the end of last year before the US launched military action against Venezuela and captured the country's president Nicolas Maduro.

'Iran may try again to obtain nuclear weapon'

Meanwhile, the Pentagon has published a new national defence strategy, which included analysis on Iran.

The document warned Iran may attempt to obtain a nuclear weapon, something it has accused Tehran's leaders of attempting before.

The document also said Iran had "the blood of Americans on its hands" and pledged US support for Israel.

It read: "Although Iran has suffered severe setbacks over recent months, it appears intent on reconstituting its conventional military forces.

"Iran's leaders have also left open the possibility that they will try again to obtain a nuclear weapon, including by refusing to engage in meaningful negotiations."

It added: "Nor can we ignore the facts that the Iranian regime has the blood of Americans on its hands, that it remains intent on destroying our close ally Israel, and that Iran and its proxies routinely instigate regional crises that not only threaten the lives of American servicemembers in the region but also prevent the region itself from pursuing the kind of peaceful and prosperous future that so many of its leaders and peoples clearly wish for."

The Duke of Sussex, who undertook two tours of Afghanistan, said British "sacrifices deserve to be spoken about truthfully and with respect".

"I served there. I made lifelong friends there. And I lost friends there. The United Kingdom alone had 457 service personnel killed," he wrote.

"Thousands of lives were changed forever. Mothers and fathers buried sons and daughters. Children were left without a parent. Families are left carrying the cost.

"Those sacrifices deserve to be spoken about truthfully and with respect, as we all remain united and loyal to the defence of diplomacy and peace."

James Rose, an Invictus Games athlete who lost both his legs above the knee while serving in Afghanistan, told Sky News presenter Barbara Serra that he has met the Duke of Sussex on several occasions and said he "is just like one of the lads".

"He served in Afghanistan twice and he served on the frontline as well," he said.

"Obviously, he set the Invictus Games up as a pathway to recovery for troops that have been injured on the frontline.

"So if we weren't serving on the frontline and being injured, then I don't think that the Invictus Games would have come about."

The rare royal rebuke came hours after Sir Keir Starmer called Mr Trump's comments "insulting and frankly appalling" - and suggested he should apologise.

Veterans and their families, as well as MPs from all parties, reacted with fury after the US president said NATO troops stayed "a little off the frontlines" in Afghanistan.

In an interview with Fox News in Davos, Mr Trump said he was not "sure" the military alliance would "be there if we ever needed them".

He added: "We've never needed them. They'll say they sent some troops to Afghanistan... and they did, they stayed a little back, a little off the frontlines."

On Friday afternoon, Sir Keir said: "I'm not surprised they've caused such hurt to the loved ones of those who were killed or injured."

He added that if he had said something like that, he would "certainly apologise".

Earlier, Downing Street said Mr Trump was "wrong" to diminish the role of NATO and British troops in Afghanistan.

The prime minister's official spokesman said UK forces had served alongside the US and NATO in "sustained combat operations".

Pointing to the 457 British deaths in Afghanistan and the "many hundreds" more who were wounded, he added: "We are incredibly proud of our armed forces and their service and sacrifice will never be forgotten."

America is the only NATO member to have invoked the collective security provisions of its Article 5 clause - that an attack against one member is an attack on all.

Trump's remarks 'the ultimate insult'

Diane Dernie, whose son Ben Parkinson suffered horrific injuries when his vehicle hit a mine in Afghanistan in 2006, said the US president's comments were "the ultimate insult".

Mr Parkinson is widely viewed as the most severely injured British soldier to have survived the war.

The blast left the former lance bombardier with both legs amputated, a twisted spine and brain damage.

His mother said: "I can assure you, the Taliban didn't plant IEDs [improvised explosive devices] miles and miles back from the front line.

"Come and look at us, the life that Ben leads - 19-and-a-half years on, still fighting for his care, still fighting for him to have a decent life, recovering from a recent operation.

"To hear this man say: 'Oh, well, you just fannied about behind the frontlines'... It's the ultimate insult."

'We shed blood, sweat and tears'

Defence minister Al Carns said: "I served five tours in Afghanistan, many alongside my American colleagues. We shed blood, sweat and tears together. Not everybody came home.

"These are bonds, I think, forged in fire, protecting the US, our shared interests, but actually protecting democracy overall."

The former commando, who served five tours in Afghanistan and was awarded the Military Cross for gallantry, said Mr Trump's comments were "ridiculous", adding: "Many courageous and honourable service personnel from many nations fought on the front line. Many fought way beyond it."

Robert Dicketts, whose son Oliver Dicketts, 27, was killed while serving with the Parachute Regiment in Afghanistan in 2006, said: "When I read it, I thought, 'What a bloody cheek!'.

"I think my thoughts about Donald Trump are probably unprintable.

"To put it politely, Donald Trump's knowledge of history is lacking considerably."

'Heroes who gave their lives in service of our nation'

The UK suffered the second-highest number of military deaths in the Afghanistan conflict. The US saw 2,461 deaths.

America's allies suffered 1,160 deaths during the conflict - around a third of the total coalition deaths.

Defence Secretary John Healey said: "NATO's Article 5 has only been triggered once. The UK and NATO allies answered the US call. And more than 450 British personnel lost their lives in Afghanistan.

"Those British troops should be remembered for who they were: heroes who gave their lives in service of our nation."

'I saw the sacrifices made by British soldiers'

Tory MP Ben Obese-Jecty, who served in Afghanistan as a captain in the Royal Yorkshire Regiment, said it was "sad to see our nation's sacrifice, and that of our NATO partners, held so cheaply by the president of the United States".

He said: "I saw first hand the sacrifices made by British soldiers I served alongside in Sangin, where we suffered horrific casualties, as did the US Marines the following year.

"I don't believe US military personnel share the view of President Trump; his words do them a disservice as our closest military allies."

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Former UK ambassador to Afghanistan Sir Nicholas Kay told Sky News the US president was "wrong" and he "clearly does not value and appreciate NATO in the same way he ought to".

"The president is wrong. He is not known for his respect for other people, and he is not known for his accuracy with facts, and I'm afraid this is another example," he said.

Last year, US vice president JD Vance hit back at claims of "disrespecting" British troops who served in Iraq and Afghanistan, after suggesting a potential peacekeeping force in Ukraine would be "20,000 troops from some random country that hasn't fought a war in 30 or 40 years".

At the time, only the UK and France had pledged troops to a potential peacekeeping force.

They described how hundreds of villages were burned to the ground, with Myanmar's military treating Rohingya males "as fair game for extermination", the author and academic said.

Thousands of people were killed and a "monstrous campaign of sexual violence" was unleashed against women and girls from the mainly-Muslim minority group, alleged victims told Dr Lee.

Now their stories are being heard directly in an international court for the first time in a landmark case, where Myanmar stands accused of committing genocide.

More than 700,000 Rohingya refugees fled the Southeast Asian country into neighbouring Bangladesh during the 2017 military crackdown.

Myanmar, which says it launched the campaign after an attack by a Rohingya insurgent group, has denied allegations of genocide.

The long-awaited International Court of Justice (ICJ) hearings began last week in The Hague, and the case is expected to set precedents about how a genocide can be defined and proven.

It was first filed by the Gambia, which has argued that Myanmar's military engaged in a "clearance operation" that violated the 1948 Genocide Convention.

The Gambia's justice minister, Dawda Jallow, said his country had brought the case out of "a sense of responsibility" following its own experience with a military government.

At the opening of the case last week, Mr Jallow told the court the Rohingya people had "endured decades of appalling persecution, and years of dehumanising propaganda".

"They have been targeted for destruction," he said.

"Myanmar has denied them their dream - in fact, it turned their lives into a nightmare, subjecting them to the most horrific violence and destruction one could imagine."

What has Myanmar said?

Myanmar, which has been under military control since 2021, opened its defence in the case, with representative Ko Ko Hlaing telling the court the country was "not obliged to remain idle and allow terrorists to have free rein of northern Rakhine State".

He added the case will be decided "on the basis of proven facts, not unsubstantiated allegations" and "emotional anguish and blurry factual pictures are not a substitute for rigorous presentation of facts".

Who are the Rohingya?

More than a million Rohingya people lived in Myanmar at the start of 2017, with the majority in Rakhine State in the west of the country.

With their own language and culture, they say they are descendants of Muslim traders who have lived in the region for generations.

But Myanmar, a predominantly Buddhist country, has long considered the Rohingya people to be illegal immigrants from neighbouring Bangladesh and denied them citizenship.

Following the 2017 crackdown, more than a million Rohingya people are now in chaotic, overcrowded camps in Bangladesh.

A UN fact-finding mission concluded the military offensive had included "genocidal acts". Myanmar authorities rejected that report, saying the military offensive was a legitimate counter-terrorism campaign.

Role of Facebook

Over three weeks of hearings, the ICJ will hear from alleged victims in closed sessions - the first time their accounts have been told directly in an international court.

The case also breaks new ground by exploring the use of Facebook as the main media for allegedly distributing hate speech.

Dr Lee, whose research focuses on Myanmar, the Rohingya, genocide and hate speech, says Facebook became a key platform in the spread of anti-Muslim and anti-Rohingya messages at that time.

"Facebook was virtually unregulated within Myanmar at that time and allowed anti-Rohingya posts to proliferate on its platform," the Loughborough University expert says.

"This provided the political cover and public support to enable the Myanmar military to undertake its 2017 violence against Rohingya without any meaningful public backlash or opposition from influential political figures."

Sky News has approached Facebook for comment.

What's the likely outcome at the ICJ?

In the case against Myanmar, Dr Lee believes the Gambia has a chance of success.

"The evidence strongly indicates Myanmar's military undertook violent actions targeting Rohingya civilians because they were Rohingya," he adds.

"And the decades-long mistreatment of Rohingya by Myanmar's military and government strongly indicates a desire to destroy the Rohingya as a Myanmar community."

The trial is the first genocide case the ICJ has taken up in full in more than a decade, and its outcome could have repercussions for how future allegations are assessed, including South Africa's case accusing Israel of genocide in Gaza.

Several members of the Rohingya have made the trip to the Netherlands to attend the hearings, which are expected to last three weeks.

A final ruling is expected towards the end of 2026.

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Myanmar was initially represented at the court by Nobel Peace Prize winner Aung San Suu Kyi, who denied her country's armed forces committed genocide, telling the ICJ in 2019 that the mass exodus of Rohingya people from the country she led was the unfortunate result of a battle with insurgents.

She is now in prison after being convicted of what her supporters call trumped-up charges after a military takeover of power.

A finding of genocide may also have an impact on the ongoing investigation at another court based in The Hague, the International Criminal Court.

In 2024, the court's chief prosecutor asked judges to issue an arrest warrant for the head of Myanmar's military regime, Senior General Min Aung Hlaing, for crimes against the Rohingya.

Gen Hlaing has previously denied the allegations, and the request for the warrant is still pending.

Only Russians entered as neutrals are allowed at the upcoming Milan-Cortina Winter Olympics.

But the Paralympics could now see athletes from Russia and war ally Belarus compete under their flag again in Italy in March.

"It's unjust, and we think it's not appropriate to give the opportunity to terrorist states to make sportswashing of their crimes," Ukrainian sports minister Matvii Bidnyi told Sky News.

"We continue to underline it, to remind the International Olympic Committee and other international sports federations that this is more than just some conflict. It's an existential question."

Speaking from Kyiv, Mr Bidnyi pointed to Russian athletes being able to use sports facilities in Crimea, which was annexed from Ukraine in 2014.

That initial assault on Ukraine happened between the Olympics and Paralympics in the Russian resort of Sochi, and the all-out war on Ukraine was also launched between the two Winter Games when Beijing hosted in 2022.

It led to further and deeper sporting sanctions on Russia, which was already serving punishments for running a state-sponsored doping scheme focused around the 2014 Sochi Games.

The International Olympic Committee (IOC) banned Russia for breaching its charter for incorporating sports entities in occupied areas of Ukraine.

And IOC president Kirsty Coventry has not supported the International Paralympic Committee lifting its ban on Russia after claiming there was less evidence of athletes being used to back the conflict.

Mr Bidnyi said: "How can I look at the Russian flag and shake hands with Russian athletes who support the war or - even not maybe strong support - but are still silent?"

In the last week, Ukrainian President Volodymyr Zelenskyy introduced sanctions on the Russian Paralympic Committee and its leader for using sport to justify the war and spread anti-Ukrainian narratives.

"We have a lot of evidence this organisation, the Paralympic Committee of Russia, supports the war," Mr Bidnyi said.

Their position is backed by more than 30 countries, including Britain.

"We opposed Russia and Belarus returning to the fold under their own flag," ParalympicsGB chef de mission Phil Smith told Sky News.

"We were very vocal about that and have been one of the nations who have really spoken out. So our position is we don't believe Russia or Belarus should be at the Paralympic Games."

But who will be competing is still unclear, due to qualification timelines and separate punishments from sports federations.

"We know there is an opportunity for athletes potentially to be handed wild card positions closer to the Games, and if they do so, then they will compete under the Russian flag after the decision of the IPC and the membership to reinstate Russian athletes," Mr Smith said.

"At the moment, we don't know whether that will happen or not, but we're obviously prepared to know that if it does happen, we will be ready and making sure that our athletes are just focusing on their performance and how they represent Paralympics GB at the Games."

Hundreds of athletes have been killed in the war and facilities destroyed in Russian attacks, including a Winter Games training base for biathlon in Chernihiv that was bombed while the Russian military charged towards Kyiv in 2022 before failing to capture the capital.

The sports minister personally hopes one day Russia will compensate them for the sports facilities left in ruins.

"I would like the war to stop, I want Russia to go out from occupied territory," Mr Bidnyi said. "And I would like Russia to pay for destroying our cities and infrastructure."

The party has published a timetable, with the whole selection process being completed next Saturday, suggesting Labour could be planning a dash to the polls as early as next month.

As the prime minister's popularity has plunged in opinion polls, allies have urged Mr Burnham - Labour's king of the north - to return to the Commons, potentially to seize Sir Keir Starmer's crown.

Today he received a top endorsement when former deputy prime minister Angela Rayner said Mr Burnham should be allowed to stand in the forthcoming by-election.

But in an announcement at 5pm on Friday, the party's ruling national executive declared that he has only until 5pm on Saturday to seek permission to stand as a by-election candidate.

That means he only has hours to make up his mind on a decision that will make or break his political career: whether to stand in the looming Gorton and Denton by-election, or wait for another opportunity.

As well as the 24-hour ultimatum facing Mr Burnham, the rest of the timetable for the by-election is brutally short. Applications opened at 5pm on Friday and will close at midnight on Sunday night.

A longlist of candidates, probably six, will be drawn up on Monday by a selection panel, shortlisting interviews will be held on Tuesday and hustings and selection will take place next Saturday.

If Mr Burnham does apply and is selected, the constituency in Greater Manchester, where Mr Burnham has been mayor since 2017, is set to host the most high-profile box-office by-election in decades.

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The by-election has been triggered by the resignation on health grounds of former minister Andrew Gwynne, who was revealed last year to have sent racist and sexist WhatsApp messages.

But although Labour is defending a majority of 13,413, and won more than 50% of the vote at the general election, Mr Burnham faces several hurdles and a "stop Burnham" campaign by allies of the prime minister.

At Labour's conference last autumn, Mr Burnham faced a backlash from Starmer loyalists after criticising the government and claiming that he had been urged by Labour MPs to stand for leader.

As well as a rule stating that elected mayors must seek the permission of the national executive before seeking nomination as a parliamentary candidate, Mr Burnham would have to quit as mayor.

That would trigger a costly election for his successor, which Labour could lose, given the unpopularity of Sir Keir's government and the current surge in support for Reform UK and the Green Party.

Also, if the national executive bows to pressure from a "stop Burnham" campaign, it could thwart Mr Burnham by imposing a women-only or black, Asian and minority ethnic-only shortlist.

Another risk is that even if he is Labour's by-election candidate, he could lose. That would almost certainly mean the end of his political career, since there would be no second chance to challenge Sir Keir.

In a by-election last year in Runcorn and Helsby, Reform UK, second in Gorton and Denton in 2024, overturned a Labour majority of 14,696 and won by a wafer-thin majority of just six votes.

If he stands in Gordon and Denton, Mr Burnham could also be opposed by George Galloway, who defeated Labour in a 2024 by-election in Rochdale, and Zack Polanski, the Green Party leader.