This is not a threat, but a realistic option. EU should take all of UK's potential approaches seriously, rather than acting and responding like we should be appeasing them.
RT @CityAM: Britain warned threats from UK govt to blow up Brexit protocol ‘have gone down really badly’ with EU https://www.cityam.com/britain-warned-threats-from-uk-govt-to-blow-up-brexit-protocol-have-gone-down-really-badly-with-eu/?utm_source=dlvr.it&utm_medium=t…