Mohammad Asim Bashir, 31, in June admitted driving Jihad Al-Shamie to the UK Defence Academy in Oxfordshire, central England, in August 2025 to carry out hostile reconnaissance.
Judge Bobbie Cheema-Grubb sentenced Bashir on Thursday to a minimum of 17 years in prison, describing him as a "committed jihadist" who had enthusiastically planned a terrorist attack with Al-Shamie.
Messages between Bashir and Al-Shamie included discussions about violence and revealed their anti-Semitic views.
Six weeks after their trip to Oxfordshire, Al-Shamie drove a car into pedestrians before attacking people with a knife at the Heaton Park Hebrew Congregation Synagogue.
One Jewish worshipper died from stab wounds and another was accidentally shot dead by the police.
Al-Shamie, a 35-year-old British citizen of Syrian descent, told police he was acting for Islamic State before officers shot him dead.
Prosecutors said at Bashir's sentencing at Manchester Crown Court that Al-Shamie was arrested twice before his fatal attack: in February 2025 for allegedly breaching a non-molestation order and again in September for an alleged rape.
His mobile devices were seized but it was not until after Al-Shamie's attack that the material on them was examined, the court heard.
Chief Constable Stephen Watson from Greater Manchester Police (GMP) said he was "deeply sorry" that the force did not review the data that contained significant evidence of Al-Shamie's mindset.
"It is clear that our not having reviewed the data available to us prior to the attack constitutes a missed opportunity," Watson said in a statement.
Prosecutors said Bashir had driven Al-Shamie on a 10-hour round trip from Manchester to the UK Defence Academy, which provides defence and security education to armed forces and government personnel, in August 2025.
In October that year, Al-Shamie attacked the Heaton Park synagogue before calling police and saying: "I pledge allegiance to the Islamic State and I have killed two Jews."
GMP's Watson said it was for the Independent Office for Police Conduct and inquests into the deaths to "determine the impact of not reviewing the contents of the devices".
"There can, however, be little doubt that the information contained within these devices would have inspired further investigative action," he said.
