On the eve of a visit by US President <a href="https://www.thenationalnews.com/tags/joe-biden/" target="_blank">Joe Biden</a>, a petrol bomb attack on police was a reminder of the continued threat of violence in <a href="https://www.thenationalnews.com/tags/northern-ireland" target="_blank">Northern Ireland</a>. Roads have been cordoned off in Belfast and events cancelled to make way for a massive police operation as <a href="https://www.thenationalnews.com/world/uk-news/2023/04/11/joe-biden-ireland-visit-excited/" target="_blank">Mr Biden flies in on Tuesday evening</a>. Monday's 25th anniversary of <a href="https://www.thenationalnews.com/world/uk-news/2023/04/10/what-was-the-good-friday-agreement/" target="_blank">the Good Friday peace agreement</a> was marred by improvised bombs being thrown at a police Land Rover during a republican rally in Derry, also known as Londonderry. A public safety operation was underway at the city cemetery on Tuesday following the republican commemoration after police said a suspicious device was found inside the grounds of the cemetery at dawn. The violence, in which police officers were unharmed, took place in the Creggan area of the city where journalist Lyra McKee was shot dead during rioting in 2019. Police raids have taken place in recent days in Derry as part of an investigation into the New IRA, one of several republican splinter groups that reject the Good Friday Agreement. Despite <a href="https://www.thenationalnews.com/world/uk-news/2023/04/11/joe-biden-ireland-visit-cousins/" target="_blank">Mr Biden visiting</a> to applaud the “tremendous progress” since 1998, politicians found themselves once again condemning violence on a day meant to celebrate Northern Ireland’s fresh start. “It is especially depressing to see the involvement of young people in the midst of the rioting,” said Rachael Ferguson, a Derry councillor from the non-sectarian Alliance Party. “We are seeing many people born after the agreement out risking their futures. The criminal godfathers will remain faceless in the shadows, teaching the younger generation hate and violence.” Mike Nesbitt, a former leader of the Ulster Unionist Party, said it was “so sad” to see the violence by “young, masked men” coincide with the peace deal anniversary. “They may think they’re changing society for the better,” he said, but one day “they will regret they have changed their own lives for the worse”. A commonly held sentiment in the run-up to the anniversary has been that violence may have subsided since 1998, but the underlying social divisions between republicans and unionists remain. Symbols of the divide between pro-Irish Catholics and pro-UK Protestants are visible on Belfast’s streets, most notably in the “peace walls” that divide parts of the city. One such barrier in West Belfast has been newly repainted with the words “25 years of building peace” — but it continues to be locked at night. The murals that display the allegiance of Belfast streets and neighbourhoods are not mere relics of the past but are still used to send political messages. On the unionist Shankill Road, a mural was redone in a matter of days after the death of <a href="https://www.thenationalnews.com/tags/queen-elizabeth-ii/" target="_blank">Queen Elizabeth II</a>, a symbol of Britain to whom nationalist Sinn Fein MPs refused to swear allegiance. A nationalist mural contains a salute to Ben & Jerry’s ice cream after it announced a boycott of Israeli-occupied territories, in a show of republican solidarity for Palestine. Even now, most children in Northern Ireland attend segregated Protestant or Catholic schools — seen as prolonging the social divide for another generation. Jonathan Tonge, a professor of British and Irish politics at the University of Liverpool, told <i>The National</i> that Northern Ireland’s young people were the least likely to vote at elections. “They’re the least likely to say they are a unionist or a nationalist,” he said. “You might see that and think ‘that could be progress, Northern Ireland’s divisions are biodegrading’. “But young people don’t turn up on polling day. They’re the least likely to vote. So elections are contests of true believers, unionist and nationalist believers, and young people feel alienated from the political system.” One prominent young activist is Jamie Bryson, a 33-year-old unionist figure who on Monday accused Sinn Fein of radicalising the petrol bomb throwers by “consistently glorifying terrorism”. He also claimed to have been threatened by an ultra-loyalist group called the Real Ulster Freedom Fighters. Unionist anger over the post-Brexit Northern Ireland Protocol was blamed in part for an outbreak of rioting in 2021. On the other side of the divide, Britain’s MI5 security service says there are four main dissident republican groups, including the New IRA, who are prepared to use violence to achieve a united Ireland. The New IRA claimed responsibility in February for the fatal shooting of detective chief inspector <a href="https://www.thenationalnews.com/world/uk-news/2023/02/26/sixth-arrest-in-shooting-of-senior-police-officer-in-northern-ireland/" target="_blank">John Caldwell</a>. The terrorism threat level for Northern Ireland was recently raised from substantial to severe, meaning an attack is considered “highly likely”. Marches that can stir high emotions are meant to be registered with Northern Ireland’s Parades Commission, which had 47 events on the list for Easter Monday — four of them classed as “sensitive”. The commission can order bans on singing or paramilitary clothing if it fears community relations would be strained. In one case, marchers were limited to “a single drumbeat”. However, the Creggan rally was not properly declared and police said protesters had carried paramilitary uniforms that were set on fire. “Organisers of this parade communicated in advance their desire to have a respectful and dignified event, however, that is not what we witnessed today,” police chief superintendent Nigel Goddard said on Monday.