PARIS (Reuters) – Britain must find concrete proposals to tackle issues concerning the border between the United Kingdom and Ireland in the wake of Brexit, said French President Emmanuel Macron during a news conference with Irish Prime Minister Leo Varadkar.

“It’s up to the UK to come up with concrete proposals to minimise the impact of Brexit on the British/Irish border,” said Macron on Tuesday.

Earlier this month, Varadkar had said Ireland wanted Britain to commit to a fallback option that would avoid a customs border returning to the island of Ireland, should its plan of keeping the closest possible ties with the EU fall through.