Three men arrested shortly before Remembrance Sunday plotted to carry out a Lee Rigby-style beheading, a court has heard.
The Islamic State (IS) extremists were acting on a "truly chilling" fatwa calling on Muslims to arm themselves and attack "disbelieving" Westerners.
Cousins Nadir Syed, 22, and Yousaf Syed, 20, along with Haseeb Hamayoon, 28, deny planning acts of terrorism between 20 September and 7 November last year.
They were inspired by Michael Adebowale and Michael Adebolajo, who ran-over and hacked to death Drummer Rigby near Woolwich barracks in South London in 2013, even keeping photos of the killers on their phones, jurors heard.
Hamayoon also staked out and took photos of a Police Community Support Officer (PCSO) patrolling a car park at a mosque in Hounslow, west London, and bought a 'Rambo First Blood II' knife, thought to be from bladebargains.co.uk, London's Woolwich Crown Court heard.
Prosecutor Max Hill QC told jurors the fatwa was issued by IS, also known as ISIS, spokesman Abu Muhammad Al Adnani. It urged followers to rise up against Westerners and "rig the roads with explosives for them. Attack their bases. Raid their homes. Cut off their heads".
It went on: "If you are not able to find an IED (improvised explosive device) or a bullet then single out the disbelieving American, Frenchman or any of their allies.
"Smash his head with a rock, or slaughter him with a knife, or run him over with your car, or throw him from a high place, or choke him or poison him."
Mr Hill said this was "the catalyst for violence" that encouraged the trio to plot together.
When Drummer Rigby's killers were found guilty of his murder in December 2013 Nadir Syed received a message asking "Did any of ur dons go to watch d court proceedings?"
Mr Hill said: "There is a level of interest in Rigby which we say is repeated again and again and again."
He added: "Further to these WhatsApp messages demonstrating Nadir Syed's interest in the knife murder of Drummer Lee Rigby on the streets of Woolwich, his telephone handsets revealed stored images of Drummer Rigby's murderers Michael Adebowale and Michael Adebolajo with the message 'an eye for an eye, a tooth for a tooth'.
"Over one of the images was the word Mujahid meaning Islamic fighter."
Jurors were shown two images of PCSOs, one patrolling the car park of a mosque and another up close, allegedly taken by the plotters.
Mr Hill said: "There was also a stored image of a Police Community Support Officer. Why did Nadir Syed have and keep these images? It is to be noted that Haseeb Hamayoon also took photographs of a PCSO patrolling the car park at the mosque in Hounslow on 29 September 2014."
Jurors were also shown a photograph of three boys with Islamic State headbands holding a decapitated head, and a photo of two suicide bombers, both allegedly stored on Nadir Syed's phone.
Nadir Syed, from Hounslow, west London, and Yousaf Syed, from High Wycombe, Buckinghamshire, wore matching maroon jumpers and chatted and smirked as they sat in the dock. Hamayoon from Hayes, west London, sat alongside them. All three deny the charges.
The Syed cousins had both tried to catch flights to Turkey early last year and prosecutors believe they were planning to get to Syria.
Nadir was stopped from boarding because he was on bail for a public order offence, while Yousaf went no further than Turkey.
But a third traveller, Luqman Warsame, made it to Syria where he fought for IS and continued to communicate with the cousins back in Britain, the court heard.
Mr Hill said that while they were "effectively landlocked in this country" the Syeds plotted with Hamayoon and talked about terror attacks in online chat rooms
Hamayoon "was interested in purchasing large hunting knives", Mr Hill said.
He used his wife's bank account to spend £39.98 on a Rambo-style knife later found at his home, the court heard.
Writing on WhatsApp last August, Hamayoon referred to US President Obama as "that kaffir Obama... He's gonna die soon."
Nadir and Yousaf Syed mocked those killed in the 9/11 terror attacks and swapped messages about the grisly beheadings of journalists James Foley and Steven Sotloff and British aid worker Alan Henning, the court heard.
They also allegedly had images of the attack on the twin towers and the 7/7 London bombings. Nadir's telephone also had a secret pin of 77911 - referring to the terror attacks in America and Britain.
Mr Hill said: "All three defendants were demonstrating their support for ISIS and acts of terrorism in general, and were interested in knives and killings by beheading.
"All three were ready we say for the important Islamic State fatwa exhorting and encouraging such murders."