A campaign group has cast further doubt on the idea of a Boris Bridge or Burrow connecting Northern Ireland to Scotland.
The UK and Ireland Nuclear Free Local Authorities (NFLA) said it would be a real challenge to develop either project, particularly if built in an area of the Irish Sea called Beaufort s Dyke, where tonnes of surplus munitions from two world wars and radioactive waste are dumped.
A 21-mile bridge from here to Scotland was proposed by Boris Johnson in 2018, with a price tag of around £20bn - and was widely derided at the time.
But with the UK leaving the European Union in January, discussions on how to keep the union together have gathered pace.