© Reuters. United States President Joe Biden and First Lady Jill Biden leave Air Force One after landing at RAF Mildenhall prior to the G7 Summit near Mildenhall, Britain, on June 9, 2021. REUTERS / Kevin Lamarque By Steve Holland and Guy Faulconbridge CARBIS BAY, England (Reuters) – US President Joe Biden brings a serious Brexit warning to his first meeting with British Prime Minister Boris Johnson: Prevent a dispute with the European Union endangers the delicate peace in Northern Ireland. On his first trip abroad since taking office in January, Biden Johnson meets on Thursday in the English seaside resort of Carbis Bay ahead of a Friday-Sunday G7 summit, a NATO summit on Monday, a US-EU summit on Tuesday and a meeting with The Russian President Vladimir Putin in Geneva the next day. Biden will seek to use the trip to polish up his multilateral credentials after the turmoil over the presidency of Donald Trump, which has left many U.S. allies in Europe and Asia confused and some alienated. However, Biden brings an unpleasant message for Johnson, one of the leaders of the 2016 Brexit campaign: stop heated EU divorce negotiations to undermine a 1998 US-brokered peace deal known as the Good Friday Agreement that ended three decades of bloodshed in Northern Ireland. “President Biden has been crystal clear about his firm belief in the Good Friday Agreement as the basis for peaceful coexistence in Northern Ireland,” White House National Security Advisor Jake Sullivan told reporters aboard Air Force One. “Any moves that endanger or undermine it would not be welcomed by the United States,” said Sullivan, who refused to characterize Johnson’s actions as threatening the peace. The UK’s exit from the European Union has torn the peace in Northern Ireland because the bloc of 27 nations wants to protect its markets but a border in the Irish Sea separates the British province from the rest of the UK. Northern Ireland borders on the EU member Ireland. Biden will also speak about donating additional doses of COVID-19 vaccines to poor countries on Thursday. PROBLEMS The 1998 peace deal largely ended the “problems” – three decades of conflict between Irish Catholic nationalist militants and pro-British Protestant “loyalist” paramilitaries, killing 3,600 people. Biden, proud of his Irish heritage, will make a policy statement on the importance of this peace deal, Sullivan said. “He’s not making threats or ultimatums, he is simply conveying his deep conviction that we stand behind this protocol and must protect it,” said Sullivan. Although the UK officially left the EU in 2020, the two sides are still exchanging threats over the Brexit deal after London unilaterally delayed implementation of the Northern Irish clauses of the deal. The EU and Great Britain tried to solve the border puzzle with the Northern Ireland Protocol to the Brexit Agreement, which keeps the province in both the UK’s customs territory and the EU internal market. Pro-British trade unionists say the Brexit deal signed by Johnson is in breach of the 1998 peace agreement, and London said the protocol is unsustainable in its current form after interruptions in supplies of essentials to Northern Ireland. Johnson, who wrote a biography of British war leader Winston Churchill in 2014, will agree to an “Atlantic Charter” with Biden, modeled on the 1941 deal made by Churchill and President Franklin D. Roosevelt. The two heads of state and government will agree on a task force to resume the journey between the UK and the US as soon as possible.