The Commissioner of the Metropolitan Police said firearms officers are “justifiably concerned” after the sniper was charged with the murder of Chris Campa.
Mr Kaba, 24, died in Streatham Hill, south-east London, in September last year after being shot through the windscreen of an Audi car.
The police officer charged with his murder, named only as NX121 following an anonymity order granted by a district judge, appeared at Westminster Magistrates' Court and the Old Bailey on Thursday.
Sir Mark Rowley said he met with 70 firearms officers operating across London after the murder charge and understood “why many of them are considering the potential price of such heavy responsibilities”.
The Met Commissioner also said officers were concerned “as they consider how others can assess their split-second decisions years after the event, with the luxury of taking as much time as they want to do that”.
In a statement, Sir Mark said: “This week a Met firearms officer was charged with murder following the fatal shooting of Chris Kaba.
“I cannot speak to this case specifically as the proceedings are very active and I am mindful of the impact this has on everyone directly affected.
“On Thursday I met with 70 firearms officers to reflect on the events of this week.
“Like me, they understand the importance of transparency and accountability and recognize the dire consequences for all involved in the very rare instances when police use lethal force.
“This impact is compounded by the very slow speed at which investigations, trials, inquests and hearings take place, meaning that the lives of all those affected are put on hold for many years.”
Sir Mark continued: “They were understandably concerned as they thought about how others can assess their split-second decisions years after the event, with the luxury of taking as much time as they want to do this, and the effect this might have on them and their families.
“As I go about my work today, our firearms officers are on patrol and deployed on crime prevention and counter-terrorism operations as they are every day.
“Not only are they prepared to take on the armed and dangerous to protect London's communities, but they do so in recognition of the uniquely intense and long-term personal responsibility they will face for their split-second operational decisions.
“Indeed, I can understand why many of them ponder the potential price of such momentous responsibilities.
“Bravery comes in many forms.
“When officers have the levels of uncertainty and anxiety that I saw in my colleagues today, it's courageous for them to go in and do their job without knowing what incidents are in front of them.”
In the moments before the shooting, Mr Kaba had driven into Kirkstall Gardens and collided with a marked police car.
The officer fired one shot, striking Mr. Kamba in the head.
They have not been named publicly after a request for anonymity was granted in court.
Recorder of London Mark Lucraft KC told the Shooter that a trial preparation and preparation hearing will be listed for December 1, with a possible trial date of September 9 next year.
NX121 was released on bail on the conditions that he lives at a named address, surrenders his passport and does not apply for international travel documents.