THE Tanaiste, Mr Spring, has sharply criticised the "volte face" of the RUC in allowing Orange marchers down the Garvaghy Road. He said he wanted an early explanation from the British government.
"The forces of law and order cannot be thwarted by the force of numbers," he said. "We've seen that happen in the past in Northern Ireland. It's unacceptable."
Decisions such as yesterday's "could undermine the confidence of people in the ability of Northern Ireland to function".
Mr Spring was speaking in Belgrade at the end of a two day EU mission to the former Yugoslavia.
"No state should yield to the sort of pressure it appears people yielded to in the past 24 hours," he said.
"We are on the edge of the abyss in relation to Northern Ireland, going back to Northern Ireland's worst. We've got" to get people to the table to start talks. If this is the alternative to talks it creates a very bleak picture for Northern Ireland.
He said he was not aware why the talks aimed at settling the dispute had not been pursued.
"The decision was made in a precipitous way. I want to find out the reasoning behind this volte face, this total change."
Asked if it would affect Anglo Irish relations he said. "It causes a problem, but it would be unwise for me to comment until we get an explanation from London.
"The right to march must be exercised but with due regard to the rights of local communities. Marches should not take place along routes on which they are not welcome.
"We have always said there was a balance to be struck in regard to marches in Northern Ireland."