An Indian general and his wife were followed before his throat was slashed with a knife in London's West End, Southwark Crown Court has heard.
Lieutenant-General Kuldeep Singh Brar, 78, needed surgery after the attack in Old Quebec Street on 30 September.
Mandeep Singh Sandhu, 34, from Birmingham and Dilbag Singh, 36, from London, deny wounding with intent to do grievous bodily harm.
Harjit Kaur, 38, of west London, also denies the charge.
A fourth person, Barjinder Singh Sangha, 33, of Wolverhampton, has previously pleaded guilty to wounding with intent to do grievous bodily harm. A fourth man is still at large, the court heard.
Prosecutor Annabel Darlow said the victim was deliberately attacked because of his role in the Indian army's attack on the Golden Temple in Amritsar in 1984.
The Golden Temple is one of the holiest Sikh shrines and Operation Blue Star was aimed at flushing out Sikh separatists who were sheltering there. Hundreds of civilians were killed during the assault.
Lt Gen Brar was on a holiday in London with his wife Meena and the pair were walking back to the Mostyn Hotel in Bryanston Street when he was targeted.
He had to be treated for deep cuts to his face and neck.
Ms Darlow said: "Mr Brar is now retired but during his career as a general in the Indian Army oversaw a number of military operations which have made him a target for Sikh extremist groups.
"This was no random attack. This was a highly premeditated assault by people who thought about what they were doing and planned it."
The jury heard that when the defendants found out Lt Gen Brar was on a private holiday in London with no security, they made two reconnaissance missions over two days to check out his movements.
On the night of the attack Ms Kaur tailed the Indian general and his wife, following them into a casino and then a restaurant, the court heard.
She also got onto a bus with the couple.
Ms Darlow said: "She played a crucial role, silently and unobtrusively following this couple who were unaware they were being followed by a woman who was relaying information to four men that were bent on attacking Brar."
Nrs Brar, who spotted the men just before the attack, told her husband they "looked frightening and they looked like a threat".
Lt Gen Brar was ambushed by a gang of four men as the couple made their way back to the hotel.
"Sangha grabbed Mrs Brar by the throat and threw her against a wall. She started to scream very loudly and called for help," Ms Darlow said.
"General Brar was fighting as hard as he could to defend himself."
As the attackers fled, one of them dropped his mobile phone giving police important clues about the attackers.
The victim has survived several assassination attempts and still receives death threats, as the military operation "has not been forgotten", the court heard.
Indian Prime Minister Indira Gandhi was also assassinated in the aftermath of Operation Blue Star.
The trial continues.