It is reported the UK plans new legislation this week to end the legal force of customs arrangements that were designed to avoid a hard Irish border.
The Foyle MP said that every international partner can now see that this British Government is an unfit partner to undertake negotiations with.
Said Mr Eastwood: “In case there was ever any doubt, this confirms Boris Johnson’s adversarial relationship with the truth.
“After signing up to the terms of the Withdrawal Agreement in October, he’s now threatening to torpedo treaty obligations which, while far from ideal, protect the fragile progress made over decades in Ireland.
“The interests of people, businesses and communities in Northern Ireland are again being placed in extreme jeopardy as part of a political gambit by this inept government.
“We’re back to where we were a year ago – this government threatening a hard border in Ireland in the pursuit of some meaningless concept of sovereignty.
“Johnson still hasn’t learned the lessons of our past – you can’t eat a flag.
“These moves should send a very clear message to every international trading partner that the British Government is courting – Johnson is fundamentally untrustworthy and will renege on any commitment he makes if he senses some domestic advantage.
“The SDLP will join with other parties at Stormont and in Westminster to resist any attempt to renege on the Ireland Protocol,” added the Foyle MP.