Two anti-vaccine conspiracy theorists plotted to destroy 5G masts and called for MPs to be hanged, a court heard.
Darren Reynolds and Christine Grayson discussed armed uprisings and advocated violence towards those they called "traitors", Leeds Crown Court was told.
Mr Reynolds, 60, "went further" and posted extreme right-wing, anti-Semitic and racist views, jurors heard.
Both defendants deny encouraging terrorism and conspiracy to cause criminal damage.
Mr Reynolds, of Newbould Crescent, Sheffield, also denies disseminating terrorist publications and possessing documents containing information likely to be useful to a person committing or preparing an act of terrorism.
'Crossed the line'
Prosecutor Tom Storey told jurors the defendants knew each other through the social media platform Telegram, which both used regularly between 2020 and 2022.
Mr Storey said the pair subscribed to a conspiracy theory involving 5G mobile phone masts being linked to the Covid-19 vaccine, adding: "They overtly discussed the potential destruction of 5G masts, both in principle and by reference to specific masts which they felt should be targeted."
The defendants' views "crossed the line" from expressing opinions to "overtly advocating the use of violence towards those whom they regarded as traitors", the jury was told.
A crossbow and a number of bolts were found when police searched 59-year-old Ms Grayson's property on Boothwood Road in York.
Officers found two replica assault rifles at Mr Reynolds' address.
'Hang them all'
The court heard both defendants were strongly opposed to the rollout of the 5G network and regarded 5G masts as pieces of "enemy infrastructure which they were entitled to disable or destroy".
Posting online on 29 June 2021, Mr Reynolds wrote: "Storm Parliament and the Lords, drag them all outside and hang them all on the spot for treason."
The following June, Ms Grayson posted: "It's still lawful to hang for treason."
Mr Storey said the "terrorist publications" Mr Reynolds was accused of sharing included a manifesto written by Anders Breivik - who was responsible for murdering some 69 people at a youth summer camp in Norway in 2011.
The court heard Ms Grayson denied having any intention to criminally damage 5G masts, telling police any comments she may have made to that effect were made in jest.
Mr Storey said Mr Reynolds felt that all his communications were "lawful, given his right to freedom of speech".
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