Brexit: Three things to look for as Washington pressures Boris Johnson to back down from Ireland proposal

While Democrats have issued warnings of their own to Johnson, Republicans have been far more circumspect, writes US political correspondent Griffin Connolly

From left, Congressman Peter King, R-NY, Irish Minister for Enterprise, Trade and Employment Leo Varadkar, Speaker Nancy Pelosi, and House Ways and Means Chairman Richard Neal descend the steps of the US Capitol in March. All three US lawmakers have fiercely defended the Good Friday Agreement. (Getty Images)

As Prime Minister Boris Johnson continues to threaten closing the border between the province of Northern Ireland and the Republic of Ireland amid Brexit negotiations with the EU, American lawmakers have re-traced a longstanding red line of their own: If the UK closes the Irish border in violation of the Good Friday Agreement, there will be no US-UK trade deal.

The 1998 accords that marked the end of the Troubles, demilitarised the Irish border, and allowed for the free flow of commerce across it has enjoyed bipartisan support in the US since its signing.