Sinn Fein, the former political wing of the Irish Republican Army (IRA), hailed its first victory in a Northern Ireland Assembly election as a "defining moment" for the British-controlled region and called for a debate on a united Ireland. #NorthernIreland #SinnFein #UnitedKingdom #News #Reuters Subscribe: http://smarturl.it/reuterssubscribe Reuters brings you the latest business, finance and breaking news video from around the globe. Our reputation for accuracy and impartiality is unparalleled. Get the latest news on: http://reuters.com/ Follow Reuters on Facebook: https://www.facebook.com/Reuters Follow Reuters on Twitter: https://twitter.com/Reuters Follow Reuters on Instagram: https://www.instagram.com/reuters/?hl=en