Terrorists have a greater chance of getting guns as a rise in the number of firearms on the streets has fuelled an increase in the number of shootings, Britain's most senior police officer has said.
There has been a 19% rise in the number of shootings in the UK since 2013/14, and Metropolitan Police Commissioner Sir Bernard Hogan-Howe believes this is because there are more weapons available to criminals.
Scotland Yard has launched a crackdown called Operation Viper in six gun crime hotspots following a "significant" increase in shootings in the capital in the past three months.
Sir Bernard said: "The potential is that more guns have got through than we've known about and they've got in to the hands of criminals. That's the best explanation at the moment.
"Clearly in some areas there is a gang element to it but that doesn't account for all of it. The fact that we're seeing it across the country in the big cities probably indicates that we're talking about more supply."
He went on: "The French and the Belgians accept that in the last 10 years criminals have got more access to weapons, particularly automatic weapons, who have then been the source for the terrorists.
"If your general supply is higher, the chances of a terrorist getting hold of them are also higher."
Last month two Islamic extremists, who turned to a criminal armourer to provide them with guns, received lengthy jail terms at the Old Bailey.
Tarik Hassane and Suhaib Majeed contacted Nathan Cuffy to arm up as part of a deadly plan to murder a police officer or soldier.
The Commissioner said: "As we've seen in Europe, particularly looking at France and Belgium, if we allow easy access or allow any liberal approach to the possession of firearms for criminals, then it allows the possibility that terrorists get hold of it.
"Terrorists are generally going to go to a criminal source to supply them, there's no way we want that to happen in Britain."
Scotland Yard will use so-called Viper squads to crackdown on gun crime in Newham, Hackney, Haringey, Brent, Lambeth and Southwark.
There were 226 shootings in London last year, and so far this year there have been 122, with a particular rise since March. Nationally, there has been an increase of around 19% since 2013/14.
Operation Viper, involving 50 officers, will include marksmen accompanying officers on traffic stops. The Viper squads will also carry out weapons sweeps and targeted raids.
A higher proportion of the shootings in the past three months caused injury.
In 2015, there were 19 shootings on average per month, with eight involving injuries. In the last three months there have been 27, with 15 victims injured.
Sir Bernard stressed that the difference between life and death can be "an inch, or alternatively a good surgeon".
Rewards of £2,000 are being offered for information that leads to the seizure of guns and prosecution of criminals linked to them.
Scotland Yard said the majority of shootings last year involved handguns. In 2015, 56% were handguns, 27% shotguns, 2% automatic weapons and 15% unknown or converted imitations.
Among victims 42% had links to gangs, and half of victims had links to drug dealing.