The UK is “first in line” for a trade deal with the US, President Trump’s national security adviser has said.
John Bolton said the US supported a no-deal Brexit and added that Washington would propose an accelerated series of trade deals.
Mr Bolton claimed deals could be done on a “sector-by-sector” basis, with an agreement on manufacturing made first.
However, critics warned the UK would have to give in to some US demands in return for any trade agreement.
His comments came after meeting Prime Minister Boris Johnson at No 10.
According to Mr Bolton, a bilateral agreement or “series of agreements” could be carved out “very quickly, very straight-forwardly”.
While saying that “both President Trump and I were leavers before there were leavers”, he added that a trade deal for financial services and agriculture would not be the first to be agreed.
Mr Bolton said “doing it in pieces” is not unprecedented and the US understood the importance and urgency of “doing as much as we can agree on as rapidly as possible because of the impending 31 October exit date”.
He argued that there would be enthusiastic bipartisan support in Congress for speedy ratification at each stage.
However, Sam Lowe, a trade expert at the Centre for European Reform said he was sceptical about whether Congress would support a “sector-by-sector” approach and the US had previously rejected an offer from the EU to negotiate on industrial goods before reaching an agreement on agriculture.
“The reason the US said no is because its aggressive ask when it negotiates with new partners is agriculture – that’s what it cares about,” he said.
Nancy Pelosi, who leads the Democrats in the House of Representatives, has also suggested a US-UK trade deal is not guaranteed. In April she said a deal was “not on the cards” if Brexit damaged the Good Friday peace agreement in Northern Ireland.
Who is John Bolton?
Considered a hawkish conservative, John Bolton rose to prominence in the George W Bush administration.
A strong defender of wielding American power abroad, he remains an unapologetic supporter of the 2003 Iraq War.
More recently he has also taken a belligerent stance on North Korea and Iran, opposing the Iran nuclear deal and advocating the use of military force against both countries.
His appointment as President Trump’s national security adviser in March 2018 was a somewhat unusual choice given President Trump’s regularly espoused non-interventionism, although the pair share similar views on Iran.
The role means he is a key adviser to the president on national security and foreign policy issues and acts as a conduit for policy proposals coming from various government departments, including defence and state.
Following his meeting with Mr Johnson on Monday, Mr Bolton said: “To be clear, in the Trump administration, Britain’s constantly at the front of the trade queue, or line as we say.
When asked whether his proposed plan would follow World Trade Organisation rules, he said “our trade negotiators seem to think it is”.
By BBC economics correspondent Andrew Walker
There is a problem with sector by sector trade agreements. They are not compatible with WTO rules, which say that free trade agreements for goods should cover “substantially all the trade”.
There is no formal definition of that term but a figure of 90% has often been suggested.
What is reasonably clear is a deal covering a few sectors would not qualify. Other WTO members could start a dispute and would, on the face of it, have every chance of winning.
However, it does not mean it would be impossible to do it. WTO rules are not enforceable in national courts so if the UK and the US wanted to go ahead they probably could.
But it would be a strange move for any country that is committed to the rules based global trade system that has the WTO at its heart.
There is another problem for any trade agreement, whether it meets the “substantially all the trade” criterion or not – it would need to be ratified by the US Congress.
There is a substantial body of American legislators who would be likely to vote against if they thought that Brexit had taken place in a way that posed a danger to the peace process and the open border on the island of Ireland.
Mr Bolton also criticised the European Union.
“The fashion in the European Union when the people vote the wrong way from the way that the elites want to go is to make the peasants vote again and again until they get it right,” he said.
He made it clear that the US government “fully understands” that Brexit is the UK’s first priority, and said issues like Iran, China, and the involvement of the Chinese telecoms firm Huawei in building the UK’s 5G mobile infrastructure could be put off until after the UK leaves the EU.
Mr Bolton also referenced Mr Johnson’s willingness to participate in Operation Sentinel, which aims to beef up the military presence in the Gulf in the face of tensions between the West and Iran, saying he was “pleased” as this “reflects a change” from Theresa May’s government.
Former Labour foreign secretary Jack Straw described Mr Bolton as “dangerously bellicose”, and suggested the UK would have to agree to some US demands, for example allowing imports of US chlorine-washed chicken.
“This is a highly transactional administration… you don’t get something for nothing,” he told BBC Radio 4’s Today programme.
Lewis Lukens, a former deputy chief of mission at the US Embassy in London and former acting US ambassador, said Mr Bolton was aligned to President Trump’s “America first agenda” and would be making “strong demands” on the UK to back the US position on issues like Huawei, China and Iran.
For example, he said Mr Bolton would want a “clear indication” from the UK it would leave the Iran nuclear deal, which President Trump withdrew the US from in May 2018.
Mr Johnson is expected to have his first face-to-face meeting as prime minister with Mr Trump later this month at the G7 summit in France.