Britain will do "whatever it takes" to protect its territorial integrity in the increasingly bitter row over post-Brexit trading with the European Union, Prime Minister Boris Johnson said, threatening emergency measures if no solution was found.
Since Britain completed its exit from the EU late last year, relations between the two have soured, with both accusing the other of acting in bad faith over part of their Brexit divorce deal that covers border issues with Northern Ireland.
The two sides showed little sign of defusing their row during meetings in the margins in the G7 summit in Cornwall today.
Despite US President Joe Biden encouraging them to find a compromise, Mr Johnson's words indicated no softening of his position over the Northern Ireland protocol.
"I think we can sort it out but... it is up to our EU friends and partners to understand that we will do whatever it takes," Mr Johnson told Sky News.
"I think if the protocol continues to be applied in this way, then we will obviously not hesitate to invoke Article 16," he added, referring to a safeguard clause that allows either side to take measures if they believe the agreement is leading to economic, societal or environment difficulties.
"I've talked to some of our friends here today, who do seem to misunderstand that the UK is a single country, a single territory. I just need to get that into their heads."
His words came after he met French President Emmanuel Macron, German Chancellor Angela Merkel and top EU officials Ursula von der Leyen and Charles Michel at the summit.
The EU told Britain once again that it must implement the Brexit deal in full and introduce checks on certain goods moving from Britain to Northern Ireland.
Britain again called for urgent and innovative solutions within the protocol.
"Both sides must implement what we agreed on," Ms von der Leyen, European Commission President, said after meeting Mr Johnson alongside Mr Michel, the European Council President.
"There is complete EU unity on this," she said, adding that the deal had been agreed, signed and ratified by both Mr Johnson's government and the EU.
Ms Merkel called for a "pragmatic solution" to the issue of post-Brexit trade in Northern Ireland.
In a news conference posted online, she said she "had advocated a pragmatic solution" to the issue during her bilateral meeting with Mr Johnson.
The United States has expressed grave concern the dispute could undermine the 1998 Good Friday Agreement.
Though Brexit was not part of the formal agenda for the G7 summit in the English seaside resort of Carbis Bay, it has more than once threatened to cloud the meeting.
France's Mr Macron offered to reset relations with Britain as long as Mr Johnson stood by the Brexit deal - a characterisation of the meeting that was rejected by the British team.
Brexit has also strained the situation in Northern Ireland, with the protocol agreed as a way to preserve the EU's single market after Britain left.
The head of the World Trade Organization, meanwhile, said she hopes that post-Brexit tensions between Britain and the European Union would not escalate into a trade war.
"I would really, really hope that a UK-EU trade war will not take place," WTO Director-General Ngozi Okonjo-Iweala said.
"With all the opportunities there are too for dialogue, I would be a little surprised if we ended up with a UK-EU trade war," she said.
"It's too costly for both sides. This is not what the world needs right now."
