Northern Ireland Unrest Explainer FILE - In this Wednesday, April 7, 2021 file photo, police form a line on the Springfield road to stop Nationalists and Loyalists attacking each other, as a hijacked bus burns in the distance in Belfast, Northern Ireland. The chaotic scenes during a week of violence on the streets of Northern Ireland have stirred memories of decades of Catholic-Protestant conflict, known as “The Troubles.” A 1998 peace deal ended large-scale violence but did not resolve Northern Ireland’s deep-rooted tensions. (AP Photo/Peter Morrison, File)Photo by: Peter Morrison/AP Northern Ireland Unrest Explainer FILE - In this Wednesday, April 7, 2021 file photo, a firework explodes as Nationalist and Loyalist rioters clash with one another at the peace wall on Lanark Way in West Belfast, Northern Ireland. The chaotic scenes during a week of violence on the streets of Northern Ireland have stirred memories of decades of Catholic-Protestant conflict, known as “The Troubles.” A 1998 peace deal ended large-scale violence but did not resolve Northern Ireland’s deep-rooted tensions. (AP Photo/Peter Morrison, File)Photo by: Peter Morrison/AP Northern Ireland Unrest Explainer FILE - In this Wednesday Oct. 16, 2019 file photo motorists pass along the old Belfast to Dublin road close to the Irish border in Newry, Northern Ireland. The chaotic scenes during a week of violence on the streets of Northern Ireland have stirred memories of decades of Catholic-Protestant conflict, known as "The Troubles." A 1998 peace deal ended large-scale violence but did not resolve Northern Ireland's deep-rooted tensions. (Photo/Peter Morrison, File)Photo by: Peter Morrison/AP Northern Ireland Unrest Explainer FILE - In this Wednesday, April 7, 2021 file photo, Nationalists and Loyalists clash with one another at the peace wall on Lanark Way in West Belfast, Northern Ireland. The chaotic scenes during a week of violence on the streets of Northern Ireland have stirred memories of decades of Catholic-Protestant conflict, known as “The Troubles.” A 1998 peace deal ended large-scale violence but did not resolve Northern Ireland’s deep-rooted tensions. (AP Photo/Peter Morrison, File)Photo by: Peter Morrison/AP Northern Ireland Unrest Explainer FILE - In this Thursday, April 8, 2021 file photo, a man walks past a burnt out bus on the Shankill road in West Belfast, Northern Ireland. The chaotic scenes during a week of violence on the streets of Northern Ireland have stirred memories of decades of Catholic-Protestant conflict, known as “The Troubles.” A 1998 peace deal ended large-scale violence but did not resolve Northern Ireland’s deep-rooted tensions. (AP Photo/Peter Morrison, File)Photo by: Peter Morrison/AP Northern Ireland Unrest Explainer FILE - In this Thursday, April 8, 2021 file photo, a Nationalist youth is lifted off the ground by a police water cannon near the Peace Wall in West Belfast, Northern Ireland. The chaotic scenes during a week of violence on the streets of Northern Ireland have stirred memories of decades of Catholic-Protestant conflict, known as “The Troubles.” A 1998 peace deal ended large-scale violence but did not resolve Northern Ireland’s deep-rooted tensions. (AP Photo/Peter Morrison, File)Photo by: Peter Morrison/AP Northern Ireland Unrest Explainer FILE - In this Wednesday, April 7, 2021 file photo, hijacked cars burn at the peace wall on Lanark Way as rioting broke out in West Belfast, Northern Ireland. The chaotic scenes during a week of violence on the streets of Northern Ireland have stirred memories of decades of Catholic-Protestant conflict, known as “The Troubles.” A 1998 peace deal ended large-scale violence but did not resolve Northern Ireland’s deep-rooted tensions. (AP Photo/Peter Morrison, File)Photo by: Peter Morrison/AP Northern Ireland Unrest Explainer FILE - In this Wednesday, April 7, 2021 file photo, Nationalists from the mainly Catholic Springfield road area of West Belfast clash with police in Northern Ireland. The chaotic scenes during a week of violence on the streets of Northern Ireland have stirred memories of decades of Catholic-Protestant conflict, known as “The Troubles.” A 1998 peace deal ended large-scale violence but did not resolve Northern Ireland’s deep-rooted tensions. (AP Photo/Peter Morrison, File)Photo by: Peter Morrison/AP Britain Northern Ireland Ulster Protest A car burns after it was hijacked by Loyalists at the Cloughfern roundabout in Newtownabbey, Belfast, Northern Ireland, Saturday, April 3, 2021. Masked men threw petrol bombs and hijacked cars in the Loyalist area North of Belfast. Loyalists and unionists are angry about post-Brexit trading arrangements which they claim have created barriers between Northern Ireland and the rest of the UK. (Peter Morrison/PA via AP)Photo by: Peter Morrison/AP Britain Northern Ireland Ulster Protest A man walks past a burning car that was hijacked by Loyalists at the Cloughfern roundabout in Newtownabbey, Belfast, Northern Ireland, Saturday April 3, 2021. Masked men threw petrol bombs and hijacked cars in the Loyalist area North of Belfast. Loyalists and unionists are angry about post-Brexit trading arrangements which they claim have created barriers between Northern Ireland and the rest of the UK. (Peter Morrison/PA via AP)Photo by: Peter Morrison/AP Britain Northern Ireland Ulster Protest Masked loyalists are seen after hijacking and setting a car on fire at the Cloughfern roundabout in Newtownabbey, Belfast, Northern Ireland, Saturday, April 3, 2021. Masked men threw petrol bombs and hijacked cars in the Loyalist area North of Belfast. Loyalists and unionists are angry about post-Brexit trading arrangements which they claim have created barriers between Northern Ireland and the rest of the UK. (Peter Morrison/PA via AP)Photo by: Peter Morrison/AP Britain Northern Ireland Ulster Protest The Police Service of Northern Ireland comes under attack by Loyalists at the Cloughfern roundabout in Newtownabbey, Belfast, Northern Ireland, Saturday, April 3, 2021. Masked men threw petrol bombs and hijacked cars in the Loyalist area North of Belfast. Loyalists and unionists are angry about post-Brexit trading arrangements which they claim have created barriers between Northern Ireland and the rest of the UK. (Peter Morrison/PA via AP)Photo by: Peter Morrison/AP Northern Ireland Unrest Explainer FILE - In this Monday Oct. 14, 2019 file photo people walk past pro-Brexit graffiti in West Belfast Northern Ireland. The chaotic scenes during a week of violence on the streets of Northern Ireland have stirred memories of decades of Catholic-Protestant conflict, known as "The Troubles." A 1998 peace deal ended large-scale violence but did not resolve Northern Ireland's deep-rooted tensions. (AP Photo/Peter Morrison, File)Photo by: Peter Morrison/AP Northern Ireland Unrest Explainer FILE - In this April 10, 1998, file photo, from right, British Prime Minister Tony Blair, U.S. Sen. George Mitchell, and Irish Prime Minister Bertie Ahern, pose together after they signed the Good Friday Agreement for peace in Northern Ireland. The chaotic scenes during a week of violence on the streets of Northern Ireland have stirred memories of decades of Catholic-Protestant conflict, known as "The Troubles." A 1998 peace deal ended large-scale violence but did not resolve Northern Ireland's deep-rooted tensions. (AP Photo/File)Photo by: Dan Chung/AP Northern Ireland Unrest Explainer FILE - In this May 5, 1981 file photo British troops, in foreground, clash with demonstrators in a Catholic dominated area of Belfast, Northern Ireland. The chaotic scenes during a week of violence on the streets of Northern Ireland have stirred memories of decades of Catholic-Protestant conflict, known as "The Troubles." A 1998 peace deal ended large-scale violence but did not resolve Northern Ireland's deep-rooted tensions. (AP Photo, File)Photo by: Anonymous/AP Northern Ireland Unrest Explainer FILE - In this Aug. 1972 file photo British troops watch as members of the Ulster Defence Association parade through Belfast, Northern Ireland. The chaotic scenes during a week of violence on the streets of Northern Ireland have stirred memories of decades of Catholic-Protestant conflict, known as "The Troubles." A 1998 peace deal ended large-scale violence but did not resolve Northern Ireland's deep-rooted tensions. (AP Photo, File)Photo by: AP