British army elite troops were on standby to step into a security crisis on Monday after scores of armed Metropolitan Police officers stood down from firearms duties following a murder charge against one of their colleagues.
More than 100 officers reportedly handed in permits allowing them to carry weapons, prompting Scotland Yard to turn to the military for assistance.
The force later said it no longer needed military support because some firearms officers had returned to armed duties.
The crisis emerged after an unnamed officer was charged with murder over the shooting of unarmed Chris Kaba, 24, who was killed in September last year in Streatham Hill, south London.
The Ministry of Defence said it had accepted a Military Aid to the Civil Authorities request from the Home Office to provide routine counter-terrorism support to the Met Police, should it be needed. It is believed the mobilised units include special forces ready in the event of any suspected terror-related incident.
Scotland Yard Commissioner Sir Mark Rowley has demanded increased legal protection for officers, while Prime Minister Rishi Sunak said armed police needed more "clarity" over their position.
Speaking during a visit to a community centre in Broxbourne, Hertfordshire, on Monday, Mr Sunak said: "Our firearms officers do an incredibly difficult job.
"They are making life or death decisions in a split second to keep us safe and they deserve our gratitude for their bravery.
"Now it is important when they are using these legal powers that they do so with clarity and they have certainty about what they are doing, especially given the lethality they are using."
In an open letter to the Home Secretary published on Sunday, Met boss Sir Mark suggested legal changes to the way self-defence is interpreted in police misconduct cases.
He welcomed a review into the situation by Home Secretary Suella Braverman and asked her to “let the police police”.
Ms Braverman said she had ordered a review to ensure armed officers “have the confidence to do their job”.
In a statement provided to The National, a spokeswoman for the Home Office said: “Firearms officers do an extremely challenging job, making split-second decisions to keep the British public safe each and every day. They have our full support.
“It is crucial that they are able to use their powers with legal certainty and clarity. That’s why we are reviewing the framework and processes in place.
"We are mindful of ongoing cases and we will not be commenting further."
Sir Mark also recommended the introduction of a criminal standard of proof for unlawful killing in inquests and inquiries, and changes to the threshold at which the Independent Office for Police Conduct can launch an investigation.
“In the UK we proudly police by consent, embracing the principles of accountability, transparency and independent scrutiny," he said in the letter.
"Of course, where wrongdoing takes place the public expect us to be held to the highest standards.
"The system that judges officers’ actions should be rooted in integrity and decisions should be reached swiftly, competently and without fear or favour.
“A review is needed to address accountability mechanisms, including the policies and practices of the Independent Office for Police Conduct and the Crown Prosecution Service, ideally with a focus on the threshold for investigating police use of force and involvement in pursuits.
“The review announced today is therefore a very welcome development."
Sir Mark called for time limits for IOPC and CPS processes to “reduce the punitive impact” on officers facing long investigations.
He added: “Carrying a firearm is voluntary. We rely on officers who are willing to put themselves at risk on a daily basis to protect the public from dangerous criminals, including terrorists.
“Officers need sufficient legal protection to enable them to do their job and keep the public safe, and the confidence that it will be applied consistently and without fear or favour.”
Asked by The National if the Prime Minister is worried the crisis could undermine the confidence of London police officers in carrying out their duties, No 10 said Mr Sunak “feels its important that they have certainty about the use of their powers”.
“That’s what the review will intend to look at and ensure that the legal and operational frameworks in which they are operating are robust and command the confidence of both the officers themselves but equally the public,” the Prime Minister’s official spokesman said.
“It is important not to delay on what is clearly an issue that is posing a challenge for the Met Police and potentially for police more widely."
Asked what Mr Sunak considers to be lacking in clarity in the current guidance, the spokesman said: “That is something that is going to be considered as part of the review.
“I think the [Home Office] department will set out the terms in a bit more detail but it is important, given the level of power that they have and indeed the level of lethality they are able to deploy – albeit in extremely rare circumstances, as borne out by the latest statistics – to consider it through this review.”
He said the probe into guidelines used by firearms officers was expected to conclude by the end of the year.
It is being carried out in conjunction with the Ministry of Justice and the Attorney General’s Office, the spokesman said.
He declined to say whether the Prime Minister was aware of the review before Ms Braverman announced it on Sunday.
A Met Police spokesman said: “The Met has a significant firearms capability and we continue to have armed officers deployed in communities across London as well as at other sites including Parliament, diplomatic premises, airports, etc.
"To ensure that we can continue to keep the public safe and respond to any eventualities, since Saturday evening Met firearms officers have been supported by a limited number of armed officers from other UK forces.
"The Ministry of Defence has agreed to a request to provide the Met with counterterrorism support should it be needed."
Ms Braverman said: “They mustn’t fear ending up in the dock for carrying out their duties. Officers risking their lives to keep us safe have my full backing and I will do everything in my power to support them.”
A Met Police officer appeared in court on Thursday in relation to the death of Mr Kaba, who died after being shot through an Audi car windscreen.
The officer accused of his murder is identified only as NX121 after a district judge granted an anonymity order.