<sod >Mr Ahern, who helped negotiate the Good Friday agreement, said Prime Minister Theresa May Brexit policy could lead to a hard border between the North and the Republic.< eod>< sod > The former taoiseach, who helped negotiate the Good Friday agreement, said Prime Minister Theresa MayÃÂ¢ÃÂÃÂs Brexit policy could lead to a hard border between the North and the Republic.< eod>