Brexit Minister Lord Frost has warned that Britain is prepared to suspend the Northern Ireland Protocol if required to protect the peace process.
In a keynote speech in Lisbon, Lord Frost stated that the protocol, which was agreed with the EU as part of the UK's divorce settlement, was not working and that it needed to be fundamentally changed if it was to survive.
If that could not be reached, he said the UK was prepared to invoke Article 16 of the protocol, which empowers either side to override significant parts of the accord.
"This government, the United Kingdom government, governs Northern Ireland as it governs the rest of the United Kingdom," he stated.
"Northern Ireland is not part of the European Union." It is our job to ensure peace and prosperity, which may necessitate the use of Article 16.
"We are not going down this road for no reason, but it is our fundamental responsibility to ensure peace and prosperity in Northern Ireland, and that is why we cannot rest until this situation is resolved."
Among the reforms sought by the UK is the replacement of the European Court of Justice's role in regulating the protocol with an international arbitration mechanism.
Lord Frost stated that revision was necessary since the protocol's operation had "shredded" the equilibrium between the two communities in Northern Ireland - unionists and nationalists.
He said there was now a "short but real opportunity" to defuse the oncoming political crisis threatening the Northern Ireland peace process, which the protocol was designed to safeguard.
"We are now in a hazardous situation." The protocol isn't operating correctly. In one community in Northern Ireland, it has completely lost support," he added.
"It is not doing what it was created to do, which is to protect the Belfast/Good Friday Agreement." In reality, it has the opposite effect. It must be altered.
"The fundamental difficulty is that we are being asked to run a full-scale EU external border through the heart of our country, to apply EU law without consent in parts of it, and to have any disputes over these arrangements resolved in one of the parties' courts."
"The way this is going is causing serious turbulence within Northern Ireland, disrupting ordinary lives, damaging large and small businesses, and causing serious turbulence within the institutions of the Belfast/Good Friday Agreement."
He added it would be a "historic misjudgment" on the EU's part to say that the protocol's provisions, drafted in "great haste," could never be amended.
"It would be to put EU internal processes ahead of alleviating turbulence in Northern Ireland; to say that societal disruption and trade distortion can be dismissed as mere background noise; perhaps even to say that they are an acceptable price for Northern Ireland to pay in order to demonstrate that 'Brexit has not worked.'"