Police and security forces must not be complacent about relative peace in Northern Ireland, MPs have been told.
Nigel Dodds, deputy leader of the Democratic Unionist Party (DUP), said the recent murder of prison officer David Black was the latest in a series of events in recent years which underlined the continued security issues.
Mr Dodds repeated concerns about the reduced security alert level on the UK mainland - from substantial to moderate - in connection to the republican threat.
He said: "There is no doubt about the progress that has been made in Northern Ireland over recent years.
"The Prime Minister's announcement yesterday is something that would have been unthinkable, he said 20 years ago, I think even 10 years ago. It is an immense opportunity for Northern Ireland to showcase its talents and the opportunities we can provide to a worldwide audience.
"It is one of the marks of the progress we have made.
"(But) people can sometimes fall into the belief that everything is now sorted out and settled as far as Northern Ireland is concerned.
"These events and the tragic murder of David Black have served to remind everyone that massive challenges remain. It is important we debate these issues here today, take note of the progress that has been made but also make clear to the people of Northern Ireland there is no complacency and there is no sense the challenges are being underestimated."