US President-elect Joe Biden said on Tuesday he did not want to see a guarded border between Ireland and the United Kingdom, adding that he had previously discussed the matter with the British and Irish prime ministers and other European leaders.
Biden had stressed the importance of protecting Northern Ireland's peace deal in the Brexit process in a call with UK Prime Minister Boris Johnson earlier in the month, after Biden won the November 3 USelection against President Donald Trump.
Johnson's government is seeking a trade deal with the European Union but says it is willing to leave without one. That could complicate the situation at the sensitive Northern Irish border with Ireland - the UK's only land border with the EU.
Biden told journalists in Wilmington, Delaware, that the border must be open.
"We do not want a guarded border," he said, answering a question from a reporter on what he would say to Brexit negotiators.
The 1998 Good Friday peace deal that effectively ended Northern Ireland's 30 years of sectarian violence created institutions for cross-border cooperation on the island of Ireland.
Johnson put forward legislation in September that would break the Northern Ireland protocol of the Brexit divorce treaty that seeks to avoid a physical customs border between the British province and EU-member Ireland.
Biden, who has talked about the importance of his Irish heritage, warned months ago as the Democratic candidate for the presidency that the UK must honor the 1998 agreement as it withdraws from the bloc or there can be no separate UStrade deal.
Johnson has never met Biden and commentators have suggested the prime minister will have to work hard to foster the "special relationship" between the historic allies.
Ireland's prime minister said on Monday he hoped the outline of a Brexit free-trade deal would emerge by the end of this week, despite what the EU negotiator called "fundamental divergences" at talks.