The phrase 'triple lock' refers to the three steps that have to be taken before more than 12 members of the Defence Forces can be sent abroad on any mission.
The first step is Government backing. That usually comes in the form of a Cabinet decision and all those decisions are taken by consensus.
The second step is a Dáil motion. Usually, the Government has a Dáil majority, so that's fairly straightforward, but the debate itself can be hot and heavy.
The third step before any deployment is the backing of the UN Security Council. And it is this third step which is the focus of political discussion.
Watch the explainer video here from Political Correspondent Paul Cunningham.
