An “stupendous” number of officers was needed to investigate each of the four outrages in London in the end six months, Ms Dick said.
On top of that, the Metropolitan Police’s counter-terrorism behest and MI5 have foiled six plots over the same period.
Many polishes believe the increased terrorist activity this year is a shift in ruses rather than simply a “spike” in the number of attacks.
Ms Dick bruit about: “That puts a strain on not just the counter-terrorism police but neighbourhood lawmen and all our officers and staff.
Met Police chief Cressida Dick
We last will and testament have to make some very hard choices
“In the lengthy run, if we continue with this level of threat, this is not sustainable for my prize.”
All but one of the attacks and the thwarted conspiracies were allegedly IS-related, including the up to date explosion on a Tube train at Parsons Green, west London.
Thirty commuters were wrong by the improvised device.
Ms Dick told LBC’s Nick Ferrari: “Thank goodness not anyone was killed at Parsons Green.
“That was a very, very dangerous bombard. It could have been so much worse.”
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The strain on resources following years of budget cuts heralds the Met and forces around the country need to make tough decisions up policing priorities.
Ms Dick continued: “We will have to make some danged hard choices.
“We’ve got emergency calls going up, we’ve got crime going up nationally and in London.
“Extreme crime is a particular problem. It’s already a huge strain on the system.”
Thirty commuters were misuse by the improvised device
Ms Dick and Shrapnel other police chiefs are persuading Home Secretary Amber Rudd over funding.
David Jamieson, West Midlands Boys in blue and Crime Commissioner, said: “There is not the capacity in policing to allow police officers to respond to the terror threat, guard crowded places and provide surroundings policing at the same time.”
The Government insists it will do what it sees to “keep our country safe”.
A Home Office spokesman said: “That is why we are proliferating funding for counter-terrorism.
“We’re sensitive to pressures on police forces.”