Police in New York City and Long Island have tightened security at public areas and are reviewing measures to protect venues used for concerts and other events — both inside and outside — following the deadly terrorist attack Monday night in Manchester.

The attack, which killed at least 22 concert goers as they left an Ariana Grande performance, spurred local law enforcement officials to review security in upcoming public events such as graduation ceremonies, New York Yankees and Mets games, the weekend Bethpage Air Show Jones Beach State Park and a Billy Joel concert Thursday in Manhattan.

The NYPD had increased the presence of its Strategic Response Group at major points in the city such as Yankee Stadium and Citi Field, even though there was no known threat against the city, said an NYPD spokesman, Stephen Davis. He said the Manchester attack is also prompting a review of how the department patrols concert venues.

“We’re keenly aware that the attackers sometimes focus not inside but outside and we make our tactical plans accordingly,” said Mayor Bill de Blasio.

Patrick Ryder, deputy commissioner of the Nassau County Police Department, said the department was moving officers from crime prevention to tactical vigilance patrols. He noted that Community Oriented Police Enforcement officers were deployed to cover this week’s Nassau Community College graduation.

“We are doing what we always do — checking bags and everything,” said Charles Lang, senior security manager for the renovated Nassau Veterans Memorial Coliseum, site of the NCC commencement. “Obviously, after last night, we are on alert.”

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Ryder said that State Police and parks police will be on hand for this weekend’s Bethpage Air Show at Jones Beach.

Suffolk County Police Commissioner Timothy Sini said in a statement that the department plans to adjust “its posture and personnel deployment, if necessary, to ensure the safety of the citizens of Suffolk County.”

The NYPD’s liaison in London briefed Commissioner James O’Neill early Tuesday about the Manchester attack before he left for Washington, D.C., where he and his counterterrorism chief John Miller had previously scheduled meetings, said a department spokesman.

New York City, experts noted, is especially challenging for law enforcement because, as was the case in Manchester, public transportation is in very close proximity to public arenas. A case in point said Davis is Madison Square Garden, which sits atop Penn Station, as well as an Amtrak station and several subways lines. Such physical closeness makes security screening difficult, he said.

“What if you wanted to catch a train home and you are coming home with a briefcase, you are going to have to go through a magnetometer? I think the logistics would be almost impossible to do,” opined one NYPD official.

Some public venues, such as Madison Square Garden, are surrounded by relatively little public space which is already patrolled by the NYPD. Over the years, the department has expanded its outside “footprint” of officers and canine patrols at venues like Citi Field, said another NYPD spokesman, Chief Timothy Trainor.

Security consultant Robert Strang, head of Investigative Management Group in New York, said the expansion of security perimeters around concert venues is one strategy. But Strang believes the best approach to stop terrorist attacks is to employ good intelligence gathering and proactive law enforcement to make arrests. If those fail, then it is up to cops on ground, he said.

“The main thing is to prevent it and using all resources and intelligence because at the end of the day, you a get a guy like this, even if you are at the outer perimeter of the outer perimeter, people will get hurt,” said Strang.

“We can only do what we can do as far as putting our people in position,” Ryder said. “But the best that we can do is get the assistance from the community and use those resources outside that can support us in our intelligence gathering. You see something, you say something.”

Local law enforcement is increasing security for the Bethpage air show, to be held on Saturday and Sunday, officials said.

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Additional officers and private security guards, who will screen all visitors’ backpacks and bags, will be deployed, said Captain Anthony Astacio, Long Island regional commander of the New York State Park Police and George Gorman, Long Island deputy regional director, New York State Office of Parks.

“That was the direct result of what happened in Manchester,” Astacio said.

Last year’s air show drew a total of 453,000 people, and after last summer’s truck attack in Nice, France, parks officials beefed up security for the 2017 air show.

“There will be additional video cameras throughout the air show, they are going to be on the roadway, and are going to be throughout the facility,” Gorman said.

The French attack also led the parks department to ring the ticket entrance at the Northwell Health theater with cement barriers.

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“We are planning to install additional barriers,” Gorman said.

— With Matthew Chayes, Joan Gralla, Mark Morales and Michael O’Keeffe