Sir Keir Starmer has delivered an emergency press conference on the growing tensions between US President Donald Trump and the UK and EU countries.
Addressing the nation, the Prime Minister vowed to "keep dialogue open" with Mr Trump, but will not hesitate to use "full strength of the Government" to "protect the security, living standards and future of the British people".
In his address, Sir Keir said: "The world has become markably more turbulent in recent weeks. Events are moving fast. And in moments like this, what matters most is being clear about the values and the interests that guide us.
"Even as circumstances change, the United Kingdom has a long history. Our values were not improvised, they were built patiently over time.
"And while we are pragmatic in how we pursue our interests, we are resolute in defending those values when it matters.
"So let me begin with the United States. The UK and the US are close allies and close partners.
"That relationship matters profoundly, not just to our security, but to the prosperity and the stability that people here depend upon.
"Under President Trump, as under previous presidents, we're determined to keep that relationship strong, constructive and focused on results, and that approach is delivering.
"Through sustained engagement, we've seen significant US investment into the UK economy running into hundreds of billions of pounds, supporting growth, skills and jobs right across the country.
"Our cooperation on defence, nuclear capability and intelligence remains as close and effective as anywhere in the world, keeping Britain safe in an increasingly dangerous environment.
"We secured good trading terms in key sectors including cars, steel, aerospace and life sciences, protecting British jobs and manufacturers.
"That is why we take the approach that we do, because it delivers concrete outcomes in the national interest.
"I talk regularly to President Trump, and my team is in daily contact with all the key figures in his administration. These relationships matter. They deliver concrete outcomes in the national interest.
"Mature alliances are not about pretending differences don't exist, they are about addressing them directly, respectfully, and with a focus on results.
"On Greenland, the right way to approach an issue of this seriousness is through calm discussion between allies.
"And let's be clear, the security of Greenland matters and it will matter more as climate change reshapes the Arctic as sea routes open and strategic competition intensifies.
"The High North will require greater attention, greater investment and stronger collective defence.
"The United States will be central to that effort, and the UK stands ready to contribute fully alongside our allies through Nato.
"But there is a principle here that cannot be set aside, because it goes to the heart of how stable and trusted international cooperation works.
"And so any decision about the future status of Greenland belongs to the people of Greenland and the Kingdom of Denmark alone.
Keir Starmer has addressed the nation following his phone call with US President Donald Trump
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"That right is fundamental and we support it. Denmark is a close ally of the United Kingdom and of the United States.
"A proud Nato member that has stood shoulder to shoulder with us, including at real human cost, in recent decades. Alliances endure because they are built on respect and partnership, not pressure.
"That is why I said the use of tariffs against allies is completely wrong. It is not the right way to resolve differences within an alliance, nor is it helpful to frame efforts to strengthen Greenland security as a justification for economic pressure.
"Such measures hurt British workers, British businesses and the British economy, and that is why I've been so clear on this issue.
"A trade war is in no one's interest, and my job is always to act in the UK's national interest.
"That is why yesterday I spoke to President Trump, to European leaders, and to the Secretary General of Nato to find a solution rooted in partnership, facts and mutual respect, because that is how strong alliances protect shared interests.
"The same is true on other issues in the Middle East. We welcome President Trump's focus on sustaining the ceasefire in Gaza and moving on to phase two. We are open to participating constructively in such efforts.
"On Ukraine, I can be brief. We strongly support efforts to bring the killing to an end and secure a ceasefire as soon as possible.
"We recognise President Trump's role in pushing that process forward, and we will work closely with the United States, Ukraine and our other allies to apply pressure where it belongs on Putin.
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Sir Keir Starmer said he was taking responsibility for 'economic stability' | PA"Finally, let me say why all this matters so directly to people here at home. In today's world, geopolitics is not something that happens somewhere else.
"It shapes the cost of energy, the price of food, the security of jobs, and the stability that families rely on to plan their lives.
"When war drives up fuel prices, it's households who feel it first. When supply chains fracture, it's small businesses and working people who absorb the shock.
"And when instability grows, it's rarely those with the most power who pay the price.
"That is why this Government's approach is rooted in a simple belief that we must use every tool of Government, domestic and international, to fight for the interests of ordinary people at home.
"That means active Government. It means taking responsibility for economic stability so that inflation is controlled, interest rates come down and family budgets are protected.
"It means stepping in where markets fail, strengthening resilience and ensuring that global shocks do not always land on the same people in the same places, the people least able to withstand them.
"That's why we've taken action to reduce energy bills, to freeze rail fares and prescription charges.
"But tackling the cost of living today also means engagement beyond our borders. It requires shaping the world around us, not retreating from it.
"It requires strong alliances, steady diplomacy and rules that reduce uncertainty rather than amplify it.
"That is why our commitment to international law and to alliance is founded on trust. It's not abstract or ideological. It's practical. It's about stability, predictability, and fairness.
"The conditions that keep prices down, job secure, and economies resilient. That is what active Government looks like in an age of uncertainty.
"Steady at home, engaged abroad and always focused on protecting the people that we serve.
Sir Keir Starmer said he will use the 'full strength of the Government' to 'protect the security, living standards and future of the British people'
| PA"Britain is a pragmatic country. We look for agreement, we believe in partnership, we prefer solutions to slogans.
"And we will not indulge in commentary and gesture politics that harm the British people.
"But being pragmatic does not mean being passive, and partnership does not mean abandoning principle.
"That is why it's important to be clear about who we stand with, what we stand for, and where our interests lie.
"This is a moment for the whole country to pull together. So I warmly welcome the support we've had with regards to Greenland and the proposed tariffs from the leader of the opposition. I thank her for her support.
"At moments like this, there will always be people who reach for the performative, who think an angry social media post or grandstanding is a substitute for hard work.
"That's an understandable instinct, but it's not effective. It never has been. It may make politicians feel good, but it does nothing for working people whose jobs, livelihoods and security rely on the relationships that we build across the world.
"So to conclude, we will work with our allies in Europe, across Nato and with the United States. We will keep dialogue open.
"We will defend international law, and we will use the full strength of Government at home and abroad to protect the security, living standards and future of the British people.
"That is the approach I will take as Prime Minister, and that is the responsibility that this moment demands."