A No 10 source who said the German chancellor Angela Merkel’s demands for Northern Ireland after Brexit had made a deal “essentially impossible” has sparked furious exchanges on social media between prominent politicians.

Donald Tusk, the president of the European council, criticised Johnson directly, tweeting it was not about “winning some stupid blame game”.

.@BorisJohnson, what’s at stake is not winning some stupid blame game. At stake is the future of Europe and the UK as well as the security and interests of our people. You don’t want a deal, you don’t want an extension, you don’t want to revoke, quo vadis? — Donald Tusk (@eucopresident) October 8, 2019

Citing the contrast between Johnson’s repeated assurances that he wants a deal, and the substance of his proposals, Tusk said: “You don’t want a deal, you don’t want an extension, you don’t want to revoke. Quo vadis? [Where are you going?]”

Scotland’s first minister, Nicola Sturgeon, was also unimpressed.

The UK government’s attempt to shift the blame for the Brexit fiasco to anyone but themselves - today it’s Merkel - is pathetically transparent. — Nicola Sturgeon (@NicolaSturgeon) October 8, 2019

The Brexit party leader, Nigel Farage, struck a strident tone, suggesting the UK now had a choice between “a clean break Brexit” or “to stay in a new militarised empire”.

No British Government could ever accept Germany telling us that part of the UK has to stay in the EU.



The choice now is clear: A clean break Brexit, or stay in a new militarised empire.



Time to choose freedom. — Nigel Farage (@Nigel_Farage) October 8, 2019

The Brexit party’s recent party political broadcast included a section that heavily implied the withdrawal agreement negotiated between Theresa May and EU, upon which it said Boris Johnson would base his deal, signed the country up for military cooperation. It also incorrectly called into question the UK’s ability to unilaterally declare war.

Earlier, responding to the unofficial No 10 briefing published on James Forsyth’s Spectator blog, which implied the UK might withhold security cooperation from EU countries that backed a Brexit extension, the Green party’s Caroline Lucas described the government’s position as “as close to blackmail as it gets”.

This is as close to blackmail as it gets



Not content with being determined to destroy UK businesses, jobs etc, Govt now threatens to sabotage the EU



This is no way to secure a #Brexit deal, and proof that the Govt doesn't want one pic.twitter.com/C8NxZ9i6WU — Caroline Lucas (@CarolineLucas) October 8, 2019

The Northern Ireland secretary, Julian Smith, issued more of a dissenting line to the bellicose no-deal rhetoric, saying that “any threat on withdrawing security cooperation with Ireland is unacceptable.”.

I am clear that any threat on withdrawing security cooperation with Ireland is unacceptable. This is not in the interest of NI or the Union. — Julian Smith MP (@JulianSmithUK) October 8, 2019

Labour’s shadow defence secretary was also unequivocal on the matter of security cooperation.