The Ministry of Defence is offering armed soldiers to support London police after dozens of Met officers handed in their weapons.
More than 100 police officers turned in permits allowing them to carry firearms, a source told the BBC.
The Met Police said the action was being taken after an officer was charged with the murder of unarmed Chris Kaba, 24.
He died after being shot in south London last year.
A Met Police officer appeared in court on Thursday.
In a statement, the Met said some officers were “worried” about how the charging decision “impacts on them”.
The MoD said it received a request – known as Military Aid to the Civil Authorities (MACA) – from the Home Office to “provide routine counter-terrorism contingency support to the Metropolitan Police, should it be needed”.
An MACA is offered to the police or the NHS in emergency situations – the military helped medical staff in the Covid pandemic and covered for striking border staff and paramedics last year.
The Met said it was a “contingency option” that would only be used “in specific circumstances and where an appropriate policing response was not available”.
Military staff would not be used “in a routine policing capacity”, it added.
The move comes after Home Secretary Suella Braverman called for a review into armed policing.
She said people “depend on our brave firearms officers to protect us”.
“In the interest of public safety they have to make split-second decisions under extraordinary pressures.”
She said that officers have her “full backing”.
“I will do everything in my power to support them,” she added.
Mr Kaba died after a police operation in Streatham Hill on 5 September 2022.
He was hit by a gunshot fired by a Met Police officer into the vehicle he was driving and died in hospital the following day, an inquest was told.
The construction worker was months away from becoming a father when he was shot.
His death prompted a number of protests.
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