The prime minister spoke after meeting key EU players in the margins of the G7 summit in Cornwall, as wrangling over the Northern Ireland protocol threatened to overshadow the gathering.
French president Emmanuel Macron on Saturday morning urged Johnson to “keep his word” and apply the protocol in full, while European Commission president Ursula von der Leyen and European Council leader Charles Michel told him to “implement what we agreed on”.
German chancellor Angela Merkel also discussed the issue in talks with Johnson, who has now hit back with a complaint that the EU was being “theologically draconian” about the deal.
Downing Street has indicated the UK would be prepared to unilaterally delay the full implementation of the protocol to prevent a ban on chilled meats crossing the Irish Sea from Great Britain.
Restrictions on British-produced chilled meats entering Northern Ireland are due to come into force at the end of the month, triggering talk of a so-called “sausage war”.
Johnson has now warned that unless there was a solution he would invoke Article 16 of the protocol which allows either side to take unilateral action to suspend the deal if its implementation were to lead to “serious economic, societal or environmental difficulties”.
Explaining his position, the PM told Channel 4 News: “It’s stated abundantly in the text that the protocol should be implemented in such a way as to ensure free trade, free movement of goods between Great Britain and Northern Ireland and all parts of the UK.
“It’s not working like that at the moment. We need to make sure it’s applied in a sensible way.
“There’s no reason at all to have prohibitions or barriers to the movement of potted plants, tractor parts, guide dogs for the blind, chilled meats - you name it - from Great Britain to Northern Ireland.”
On Sky News, he added: “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.
“I think if the protocol continues to be applied in this way, then we will obviously not hesitate to invoke Article 16, as I have said before.
“Don’t forget, the EU themselves invoked Article 16 in January, to disapply the protocol, so they can stop removal of vaccines from the EU to the UK.
“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.”
Johnson used the meetings with EU leaders to call for “pragmatism and compromise on all sides”, repeating his call to “minimise the impact [of the protocol] on the day-to-day lives of people in Northern Ireland”.
“I certainly think that the protocol is capable of being used and interpreted - by the way, up to the EU - in a pragmatic way or a theologically draconian way,” he told Channel 5.
“At the moment we are seeing... a lot of unnecessary difficulties. I think we can sort it out, with goodwill.
“What we don’t want to see is any more unnecessary barriers to trade and we want to sort it out as fast as we can, I’m sure with goodwill we can.”
Asked if there would be a trade war if agreement could not be reached, Johnson said: “The UK will do whatever we need to do to protect the UK internal market.”
“I don’t happen to think that a trade war is a very sensible or likely way forward.
“I just think that we need some pragmatic solutions.”
This article originally appeared on HuffPost UK and has been updated.