The prosecution, led by Bill Emlyn Jones KC, told the jury that Mostafa Sepahvand, 41, was to carry out the attack, while Farhad Manesh, 46, and Shapoor Noori, 57, carried out surveillance and reconnaissance. All three were born in Iran but were living in London.
The court heard that the men's targets were journalists working for Iran International, the Persian-language satellite channel that is critical of the Tehran regime and has its headquarters in London. At least two journalists linked to the channel were targeted, the prosecutor said, and at least one was to be "subjected to serious violence" as retribution and "to try to silence and deter others who might dare to voice their criticism".
Sepahvand does not deny his involvement but says he took part out of fear of the consequences of refusing. The prosecution described that as "an entirely bogus claim", arguing that he acted for money and to have a criminal conviction for theft in Iran "fixed". The court was told he was in contact with two men with Iranian telephone numbers.
Manesh and Noori are expected to say they did not know they were carrying out surveillance on behalf of Iran. All three deny the charges and face counts under the National Security Act, including "assisting a foreign intelligence service".
The prosecution said the evidence would show the defendants visited addresses linked to their targets, took photographs and video, and carried out online research about them. Iran International, which broadcasts into Iran, has been declared a "terrorist organisation" by Tehran.