Why are the UK and EU arguing over Northern Ireland?

When the UK left the European Union, both sides agreed that Northern Ireland would avoid a hard border with the Republic of Ireland, which is an EU member. Britain now wants a new deal, which the EU is offering, but with compromise. So, what's the dispute about? Join host Peter Dobbie. Guests: Owen Reidy, Assistant General Secretary of the Irish Congress of Trade Unions. Nicholas Whyte, Senior Director in Brussels for APCO Worldwide. Graham Gudgin, Research Associate at the University of Cambridge.