The Irish prime minister has called for a provision in any Brexit agreement between the EU and the UK to allow for Irish reunification in line with the terms of the Good Friday Agreement.
Enda Kenny was speaking in Brussels after meeting with European Commission President Jean-Claude Juncker.
He said German reunification provided a precedent for such a provision.
The clause would mean Northern Ireland could potentially enter into the EU without a lengthy accession process.
The taoiseach also suggested the date that most people expected Brexit would be triggered on was likely to be delayed somewhat.
Despite this, he said he hoped to attend the key meetings that will set the priorities for the Brexit talks.
Also speaking after the talks, the European Commission president said the EU does not want a hard border between Northern Ireland and the Republic.
"During the Brexit negotiations, the EU and Ireland must work together to minimise the impact," said Mr Juncker.
"We don't want hard borders between Northern Ireland and Ireland."