In order to forestall this, and to prevent a backdoor into the European Single Market, the UK proposed a backstop agreement within the Withdrawal Agreement that would put Northern Ireland under a range of EU rules in order to forestall the need for border checks. This was opposed by the subsequent British government as producing an effective border between Great Britain and Northern Ireland. In late October 2019, the UK and EU reached a Brexit withdrawal agreement which contains a revised Northern Ireland Protocol that commits the UK to maintaining an open border in Ireland, so that (in many respects), the "de facto" border is the Irish Sea.