(Bloomberg) -- House Speaker Nancy Pelosi on Thursday threatened to block any future bilateral trade agreement between the U.S. and the U.K. if Brexit puts at risk the accord that brought an end to the conflict in Northern Ireland.

“If Brexit undermines the Good Friday accord, there will be no chance of a U.S.-U.K. trade agreement passing the Congress,” Pelosi said in a statement. “The peace of the Good Friday Agreement is treasured by the American people and will be fiercely defended on a bicameral and bipartisan basis in the United States Congress.”

Pelosi’s bid to influence Brexit follows remarks in London by President Donald Trump’s top national security adviser, John Bolton, who said a bilateral trade agreement would be a top priority for the administration after U.K. exits the European Union and would get “overwhelming” support in the U.S. Congress.

“To be clear, in the Trump administration, Britain is at the front of the trade queue -- or ‘line,’ as we say,” Bolton said Monday after meeting with the U.K.’s new prime minister, Boris Johnson. He said Brexit wouldn’t threaten the Good Friday Agreement.

Brexit talks between the U.K. and the EU are currently at an impasse. If that continues, Britain will leave the EU without a deal Oct. 31, something that economists and government officials warn could cause severe economic damage.

Though Ireland and the U.K. have promised not to put physical infrastructure on the border in the event of a no-deal Brexit, in reality there will need to be some kind of customs checks at or near what will be the external frontier for the EU’s single market.

The removal of checks formed a key part of the commitment to cross-border cooperation in the 1998 Good Friday Agreement, which ended decades of violence particularly in Northern Ireland. Opponents of Brexit argue that any physical infrastructure at the border risks a return to the unrest of the past.

“The administration remains a strong supporter of the Good Friday Agreement,” Bolton said. “And we don’t see what the problem is.”

--With assistance from Robert Hutton.

To contact the reporter on this story: Erik Wasson in Washington at ewasson@bloomberg.net

To contact the editors responsible for this story: Joe Sobczyk at jsobczyk@bloomberg.net, Joshua Gallu

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