A schoolboy accused of downloading a terror manual and hoarding chemicals in his bedroom had been thrown out of school for saying: "All Americans must die", a court heard.
Waris Ali, now 18, from Ravensthorpe in Dewsbury, is charged with downloading the Anarchist's Cookbook and buying several kilos of potassium nitrate on eBay as part of a plan to bomb members of the BNP.
Leeds Crown Court heard that Ali had been thrown out of Westborough High School in Dewsbury just weeks before sitting his final GCSEs after writing: "All Americans must die" on a classroom whiteboard.
Nicola Colloby, Ali's RE teacher and form tutor, said his last few months at the school had been peppered with "disturbing" incidents which suggested he was becoming increasingly radicalised.
In his homework planner he had marked the 9/11 twin towers attacks as a key date and had openly approved of them, the court was told.
Mrs Colloby said: "He had a particular interest in politics and religion, he was very interested in what was happening in Afghanistan and Iraq, he expressed opinions about the terror attacks in America, he was of the opinion they were a good thing, that America was very much the enemy."
Mrs Colloby said that she had expressed concerns directly to Ali that "perhaps some things were not for discussion in school, that he might be offensive to some people without realising he was being."
She said: "He seemed vehement that his opinion was the right opinion. America was very much against Muslims and Islam and it was causing the problems in the world. It was all he ever wanted to discuss, it was quite disturbing."
The court heard that Ali had also put together a document called the Waris Act which he encouraged other Muslim pupils at the school to sign.
When challenged about his extreme views, the court heard Ali insisted it was his right to express his opinion.
Vanessa Ibbetson, former librarian at Ravensthorpe library, told the court he (Ali) asked how many chemicals you could keep at home before you could be suspected of being a terrorist.
Ali later told a police officer his questions were linked to him wanting to study law.
The court was also told that Ali had a "difficult" home life. His father was severely disabled, his mother barely spoke English and the lack of a father figure might have contributed to his "radicalisation".
The jury heard earlier this week that in 2007 Ali had bought several kilos of potassium nitrate and calcium chloride from eBay and had internet chats with fellow accused Dabeer Hussain about blowing up members of the BNP.
Ali of Dearnley Street, Ravensthorpe is charged with three counts of possessing an article for the purpose of terrorism. Hussain, also 18, and from Clarkson Street, Ravensthorpe, faces one similar charge.