It came as the Prime Minister warned the European Union the Good Friday Agreement was more important than the post-Brexit deal.
Ms Truss is set to tell the EU the dispute over Northern Ireland cannot drag on, after warning she will “not shy away” from taking action as she accused the EU of proposing solutions that would “take us backwards”.
Mr Carmichael, the Lib Dems Northern Ireland spokesman, accused the Conservatives of using international crises to “litigate internal Tory bun fights”.
He said: “Liz Truss cannot flip from lecturing Russia about the importance of the rule of law one day to legislating the next day to break it.
"Liz Truss appears intent on trashing the UK’s reputation as a force for the international rule of law and it is hard not to feel as though it is more about burnishing her leadership credentials than any coherent plan.
“The foreign secretary in the same breath says that the Northern Ireland Protocol is undermining stability – and that she will tear it down in defiance of the clear majority of newly-elected Northern Ireland assembly members who wish to retain it.
"Unilateral action will not stabilise Northern Ireland – it will be a license for political disaster.
"The self-absorption and self-destructive nature of this Conservative Government is the problem – no wonder voters are getting sick of them.”
At a press conference in Sweden, Mr Johnson faced questions over whether now was the right time to pick a fight with the EU against the backdrop of Russia’s invasion of Ukraine.
He said: “The most important agreement is the 25-year-old Belfast Good Friday Agreement.
“That is crucial for the stability of our country of the UK, of Northern Ireland. And it’s got to be that means that things have got to command across community support.
“Plainly the Northern Ireland Protocol fails to do that and we need to sort it out.”
Ms Truss is expected to reiterate in a call with European Commission vice-president Maros Sefcovic on Thursday the risk to the Good Friday Agreement and warn the situation cannot drag on.
Officials working for Ms Truss are drawing up draft legislation to unilaterally remove the need for checks on all goods being sent from Britain for use in Northern Ireland.
Downing Street backed Ms Truss in claiming that some EU proposals were “a backwards step”, but declined to say whether preparations have been made for a possible trade war with the bloc.
The Prime Minister’s official spokesman said: “I think we’re getting ahead of ourselves. We want nothing but good relations with our EU partners, but I’m not going to get into speculation about what might happen down the line.”
Cabinet minister Michael Gove earlier warned “no option is off the table”, and added he was “super cool” with threats to tear up the protocol.