BELFAST — US Secretary of State Hillary Clinton Friday condemned a wave of street violence in Northern Ireland, saying it showed the peace process she has long supported in the British province was not yet complete. Clinton arrived in Northern Ireland, following Dublin talks on Syria with Russian Foreign Minister Sergei Lavrov, in a week that has seen three riots and the arrest of four suspected militant nationalists after the discovery of a bomb in a car. “There can be no place in Northern Ireland for any violence, any of the remnants of the past need to be quickly, unequivocally condemned,” Clinton told a news conference she held with First Minister Peter Robinson and his deputy, former IRA leader Martin McGuinness. She said violence was from “a small minority of people who try to stir up passions or emotions. It is unacceptable and must be repudiated by everyone”. However, she said the province has been transformed since her first visit 17 years ago with her husband, then President Bill Clinton, whose efforts helped bring about the 1998 peace agreement in one of the greatest successes of his presidency. The latest riot erupted on Thursday night when a policeman was injured after protesters hurled missiles to vent their anger against nationalist councillors who voted to remove the British flag atop Belfast City Hall. Police on Friday said four men were arrested after a “viable bomb” was recovered from a car in a republican area of Londonderry overnight. A letter bomb was also found in a County Down postbox with the capacity “to kill or cause serious injury”. “Peace does need sacrifice. Compromise and vigilance day after day. We have seen this week that the work is not yet complete because we have seen violence break out again,” said Clinton, on one of her last trips as secretary of state. Clinton travelled to Northern Ireland several times in the mid-1990s while her husband helped broker the 1998 Good Friday peace accord, his hands-on approach widely recognized as crucial at moments when the agreement looked like crumbling. At least 3,600 people were killed during the previous three decades as Catholic nationalists seeking union with Ireland fought British security forces and mainly Protestant Loyalists determined to remain part of the United Kingdom. The 1998 peace has mostly held, although militant nationalists have stepped up attacks in recent years. Last month, militant nationalists shot dead a prison officer and signs at the airport where Clinton landed on Friday said “Threat Level ‘Severe'”. As first lady, Clinton supported pro-peace women's groups in Northern Ireland and visited people wounded in the 1998 Omagh bombing, the deadliest attack in three decades of violence commonly known as the “Troubles.” She was due to meet some women she has remained friends with since. During her latest visit, she emphasized the need to revitalize the economy in Northern Ireland, where house prices have fallen by over 50 percent since 2007. The troubles led to decades of under-investment and the province remains heavily dependent on a grant from London. US investment in the province totals a tiny fraction of that in the Republic of Ireland. — Reuters