The Taoiseach has warned of a possible return to cross border criminality and even armed conflict if Brexit negotiations fail to take Ireland's unique position into account.
Enda Kenny highlighted that while the UK is opting for a hard Brexit, many of their intentions will remain unclear until after Article 50 is triggered next month.
He says "new ways" of having relationships will have to be thought out or the consequences could be serious for the country.
"Any semblence to a return to what they call a hard border, or borders of the past, brings with it serious challenges for this country," he said.
"I don't mean just in terms of trade or economy, but what we had before - criminality and even armed conflict.
"I wouldn't want to be alarmist about it, but this is a political challenge here."