"Ireland's problem" means it becomes our problem as well if it results in the Good Friday Agreement being torn up and the resumption of paramilitary activity in Northern Ireland and England.
Clearly we would wish to avoid this, but in order to do so all parties must have something to lose and something to gain. If one party is expected to make all the running then the negotiations will fail and there will be no deal.
This then gives Ireland and the EU immediate problems to deal with:
- The EU will be insolvent
- Ireland must unilaterally rescind the Good Friday Agreement by imposing EU border controls