The US-UK special relationship

Where does the term ‘special relationship’ come from?

The UK and US have a long shared history and shared language, but the idea of a ‘special relationship’ between the UK and USA dates back to the end of the Second World War and the early Cold War period. Winston Churchill popularised the term in a famous 1946 speech when talking about the need to unite against the growing threat of the USSR, and it has since been adopted by successive governments when keen to emphasise Anglo-American relations. However, these are not the only countries that use the term. The phrase has been used by Israel and the United States to refer to their relationship, as well as the Canadian-American relationship in the past, while Donald Trump has also described France as the US’s “oldest ally”.

What does the special relationship entail?

The UK’s close relationship with the US is not just based on relationships between presidents and prime ministers, but on deep intelligence, defence and security working relationships. It resolves particularly around the commitment obtained from the US in the aftermath of the war to remain a guarantor of peace in Europe. This formed the basis of Western co-operation throughout the Cold War and beyond.

During the Second World War, after the 1941 Japanese attack on Pearl Harbour and the signing of the Atlantic Charter Treaty, the two countries worked very closely together in the prosecution of the war but also in the development of nuclear weapon technology. The US had also learnt from UK intelligence in building its own intelligence functions. In the aftermath of WW2, the US leant on UK intelligence capability and reach of the then British Overseas Territories and Commonwealth in order to monitor Soviet activities, particularly as the USSR had also developed a nuclear weapon. This close defence and intelligence relationship has remained the bedrock of the UK-US relationship in the decades since, even at times when relationships between the nations’ leaders were more strained.

For some historians, the very idea of a special relationship, particularly in diplomatic terms, is overdone. The supremacy of the US during the post-war period means that it has had to manage many relationships and partnerships, and there have been many times when it has looked to other parts of the world when thinking about its strategic goals.

When the US goes to war does the UK always provide military support?

As NATO members, both countries sign up to the principle that an attack on one is an attack on all. There have also been many times in the post-war period when the two countries co-operated on military interventions from the 1948 Berlin airlift and 1950– 53 Korean War, through to wars in Afghanistan and Iraq that followed 9/11. But other countries also supported the US in many of those conflicts and the UK has not always supported the US, or vice versa. In the 1960s, British prime minister Harold Wilson resisted pressure from American president Lyndon B Johnson to commit UK troops to the Vietnam War. In 1956, the US was strongly opposed to British and French military intervention in Egypt to retake the Suez canal and pressured them to accept a ceasefire. In the 1982 Falklands War, the US was initially opposed to British action but were persuaded by the Thatcher government to tacitly support the action and provided intelligence and other kinds of support.

Outside of specific conflicts, both militaries train and prepare together very closely and there are bilateral relationships at many levels of their respective armed forces. The UK has purchased US technology for its nuclear weapons capability and has adopted other kinds of US military technology that has made it quite dependent on US support at times.

What security and intelligence treaties are there between the UK and US?

The Mutual Defence Agreement (MDA) of 1958 formed the basis for subsequent UK-US defence co-operation. This treaty came after a decade and a half of the UK being cut off from US nuclear technology due to Congress banning co-operation in 1946 under the McMahon Act (both Congress and president Truman not knowing how closely the UK had been involved in the development of the bomb during the war). The two countries had been able to maintain some nuclear technology sharing in the intervening years in order to facilitate the UK’s support in monitoring Soviet nuclear weapons development, but the UK had independently developed its own bomb. 

The 1958 MDA has since formed the basis of a very close nuclear weapons relationship. From 1962, the UK has purchased nuclear weapons delivery technology while building its own submarines and warheads. This has made it reliant on US technology but has also kept it close to US advances. The current Trident missile system is now expected to continue into the 2060s but the UK is working on developing its own new generation of nuclear submarines and developing a new generation of nuclear warheads in parallel with the US programme. The US also has military bases in the UK and in other territories, including the shared UK-US Diego Garcia base in the Chagos Islands. In 2024, the UK announced that it was in discussions with Mauritius about returning sovereignty of the Chagos Islands but that it was agreeing a 99-year lease for continued use of the base. 

With Australia, New Zealand and Canada the countries are also part of an intelligence sharing relationship known as ‘Five Eyes’. This grew out of the bilateral UKUSA Agreement (The United Kingdom – United States of America Agreement) that stemmed from WW2 intelligence sharing and continued into the Cold War. This close intelligence relationship is now embedded into many working practices and automatic sharing that is not normally dependent upon prime ministerial-presidential relationships.

The UK and US are also part of a trilateral defence agreement with Australia, known as AUKUS, announced in 2021. As well as military and other technological co-operation, the agreement included Australia obtaining nuclear-powered submarines and UK and US nuclear submarines being based in Australia on a rotating basis.

Which institutions are the UK and US both members of?

Both the UK and US are currently NATO allies and permanent members of the United Nations Security Council. They are also members of international groupings such as the G7 and G20.

Which UK prime ministers and US president enjoyed the closest relationship?

The close association dates back to the relationship forged between Churchill and FDR during the Second World War. Since then there have been times when presidents and prime ministers have enjoyed a particularly close relationship. Margaret Thatcher and Ronald Reagan were close, particularly in their combined approach to the USSR, despite the pressures of the Falklands War (where others in the American administration were critical of the action) and UK criticism of the 1980 American intervention in Grenada. Tony Blair looked to the Clinton government for lessons in the run up to the 1997 general election and had a close friendship with Clinton, but also cultivated a relationship with George W Bush which became particularly important in the aftermath of 9/11 and the UK’s decision to support the American military response.

Prior to the first or current Trump presidency, the nadir is often thought to be during the premiership of Harold Wilson, who was critical of the Vietnam war in the late 1960s, but there have been many moments when the relationship became strained.

What did Brexit for mean for UK-US special relations?

Presidents Obama and Biden both made it clear that they thought Brexit was a mistake, though president Trump is a big supporter. Brexit has not in itself had any implications for the security relationships which are at the core of the special relationship. However, Brexit campaigners presented a UK-US free trade agreement as a potential big prize – the EU having failed to conclude negotiations with the US on its Transatlantic Trade and Investment Partnership (TTIP). In practice, though, any US administration would likely have demanded access to NHS contracts and a lowering of UK animal welfare standards which would have made a deep FTA with the US difficult for any UK government to agree.

While an EU member, the UK liked to see itself as a key intermediary between the US and Europe and in particular the EU – and Keir Starmer has been trying to revive that role with talk of forming a bridge. But recent US administrations have tended to focus as much on building direct bilateral relations with Germany and France as well as with the UK and there are now forums for US-EU co-operation (for example, on tech regulation) from which the UK, post-Brexit, is excluded.

Do all US presidents have state visits to the UK?

No. The special relationship does not mean any automatic state visit. There was no state visit by Joe Biden. Nor are there Royal visits to the US during every presidency.

Does Donald Trump believe in the special relationship?

President Trump has at times made much of his personal attachment to the UK – his mother was born in Scotland and he owns a golf course there. However, his ‘America First’ approach to international relations, whether security or economic, suggests little space for sentimentality. In the first weeks of his second presidency, his public statements have questioned and undermined the post-war concept of western security based on guaranteed US support, particularly with his approach to NATO and Ukraine. The vice-president JD Vance included the UK in the list of western European countries he criticised for their intolerance to what he termed free speech. Elon Musk, a closer adviser of Trump, has been very critical of the UK both during the presidential campaign and since, including declaring that “civil war is inevitable” in August 2024 during the Southport riots.

The UK’s response to the Trump presidency has been to try and foster links with the Trump presidency, particularly on a shared approach to Ukraine. Another key strategic aim will be negotiating a carve-out from the tariffs president Trump has threatened to impose on other countries – the UK’s biggest argument is that the UK does not run a surplus on trade in goods with the US. Keir Starmer’s first visit to Washington is the first test of his own attempts to forge a special relationship with the US president.