Joe Biden has “deep” concerns that a UK-EU trade row could endanger peace in Northern Ireland, his national security adviser has told the BBC.
The US president will tell fellow leaders at this week’s G7 summit that gains since the Good Friday Agreement must be protected, Jake Sullivan said.
The UK and EU are at loggerheads over checks on goods going between Great Britain and Northern Ireland.
If no compromise is reached, there are fears of potential violence in NI.
Mr Sullivan’s comments also come as the UK is trying to secure a free-trade deal with the US.
He insisted he was not trying to “negotiate in public” or issue a “warning” to Boris Johnson’s government, but merely stating “how the president feels about this issue”.
The UK and EU are in talks over simplifying the Northern Ireland Protocol, which set up a post-Brexit trade border between Northern Ireland and Great Britain (England, Scotland and Wales) in order to prevent goods checks along the Irish land border.
Some checks are taking place on British goods going to Northern Ireland, causing disruption to food supplies and online deliveries.
Unionists are strongly opposed to these because they do not want Northern Ireland to be treated differently to the rest of the UK.
And one group has written to Mr Johnson to withdraw support for the Good Friday Agreement – signed in 1998 following heavy involvement by the US – which helped bring an end to the Troubles.
In an interview with BBC North America editor Jon Sopel, Mr Sullivan said the success or failure of the Northern Ireland Protocol was “critical to ensuring that the spirit, promise and future of the Good Friday Agreement is protected”.
He urged the UK and EU to “work out the specifics” and “find a way to proceed that works for both”, adding: “But whatever way they find to proceed must at its core fundamentally protect the gains of the Good Friday Agreement and not imperil that.”
That was the “message President Biden will send” at the G7 summit, which runs from Friday to Sunday in Carbis Bay, Cornwall, Mr Sullivan said.
“We want to make sure that the work that the US, UK, and Ireland have all done, in addition to the key parties in NI, has got to be honoured and respected and protected as we go forward,” he added.
Jake Sullivan was very keen to impress upon me that, if the administration were a rock-‘n’-roll band, this would be the “America is back” tour.
He wants the world to know that the isolationist, poke-your-allies-in-the-eye Trump years are gone, that the familiar, multilateral America is returning.
Mr Sullivan argues that on climate change, the global economy and leading the world out of the pandemic, the US will play a leading role.
This will be welcomed by the other G7 nations after the bumpiness that came with his predecessor. But Mr Sullivan is aware that will be met with some scepticism too.
After the scarring events of 6 January, when Washington’s Capitol building was stormed, how can America be the role model of functioning liberal democracy? How reliable a partner will it be? Could the go-it-alone America re-emerge in four years’ time?
The UK has pushed back the full implementation of checks on supermarket goods and parcels travelling from Britain to Northern Ireland to ease disruption to supplies.
This has prompted the EU to accuse the UK of undermining the Northern Ireland Protocol and begin legal action.
The next phase of controls, on chilled meat products including sausages and mince, is due to begin on 1 July.
The UK’s Brexit minister, Lord Frost, is meeting his EU counterpart Maros Sefcovic in London to discuss ways to reduce trade disruption.
He has urged the EU to show “common sense”, but Mr Sefcovic has warned against “quick fixes” to border issues.