NEW YORK — In a city shaken by its deadliest terrorist attack since 9/11, police are promising an unprecedented security effort to try to secure a soft target spanning five boroughs and 26.2 miles: the New York City Marathon.
City officials have sought to calm the nerves of more than 50,000 runners and huge crowds of onlookers expected to line the marathon route by insisting it should go off Sunday without a hitch only days after a truck attack killed eight people in lower Manhattan.
The security detail will include hundreds of extra uniformed patrol and plainclothes officers, roving teams of counterterrorism commandos armed with heavy weapons, bomb-sniffing dogs and rooftop snipers poised to shoot if a threat emerges.
The Police Department is also turning to a tactic it has used to protect Trump Tower and the Macy’s Thanksgiving Day Parade: 16-ton sanitation trucks filled with sand. The trucks, along with ‘‘blocker cars,’’ will be positioned at key intersections to try and prevent anyone from driving onto the course.
The New York Police Department said it has no information pointing to any credible threat against the race.
President Trump said Friday the US military is attacking the Islamic State ‘‘10 times harder’’ in response to Tuesday’s New York City truck attack. Officials later said the United States had conducted two airstrikes against ISIS-affiliated fighters in Somalia.
It was not immediately clear whether the Somalia strikes were carried out as presidentially directed retaliation for the truck attack that killed eight people.
The alleged New York attacker, Sayfullo Saipov, told FBI interrogators that he was inspired by ISIS, and Trump wrote in a tweet that the group claimed Saipov as ‘‘their soldier.’’
Trump tweeted: ‘‘Based on that, the Military has hit ISIS ‘much harder’ over the last two days. They will pay a big price for every attack on us!’’
Asked about this later, Trump told reporters before he departed on his Asia trip, ‘‘What we’re doing is every time we’re attacked from this point forward — and it took place yesterday —we are hitting them 10 times harder. So when we have an animal do an attack like he did the other day on the west side of Manhattan we are hitting them 10 times harder.’’
The military’s daily rundown Friday of US and coalition airstrikes against Islamic State targets in Iraq and Syria reported nine strikes in Syria on Thursday and four in Iraq. That is consistent with strike levels throughout this week.
Asked about Trump’s assertion that the military is striking ISIS ‘‘10 times harder,’’ the Pentagon issued a brief statement saying the United States continues to strike ISIS, along with Al Qaeda and other like-minded extremist groups, ‘‘wherever they are globally and at a time of our choosing.’’
Marathoners from around the world who have been streaming into New York in anticipation of the race expressed mixed feelings about running so soon after the carnage.
There is no question that the course provides a security challenge, even for a police department with 35,000 officers.
The race starts in a relatively secure location. Runners gather at Staten Island’s Fort Wadsworth, a former military installation now partly occupied by the Coast Guard.
From there, though, the race heads through residential neighborhoods with hundreds of spots where an attacker could steer a vehicle onto the thickly packed course. Streets leading to the course are closed, but on many of them, in most years, the only barrier is a blue, wooden sawhorse and a thin plastic tape.
‘‘It will be an extraordinary event, as it always is,’’ Mayor Bill de Blasio said this week at a news conference. ‘‘It will be well protected, as it always is.’’
The Islamic State is using its propaganda to encourage radicalized ‘‘lone wolves’’ to cause harm with unsophisticated means in easily accessible settings.
An online Islamic State magazine posted last year extolled using trucks to kill innocent victims, saying, ‘‘Vehicles are like knives, as they are extremely easy to acquire.’’ It also advised ‘‘surveying the route for obstacles, such as posts, signs, barriers, humps, bus stops, dumpsters, etc. which is important for sidewalk-mounted attacks.’’
The shift away from sophisticated large-scale attacks like the one on the World Trade Center’s twin towers on Sept. 11, 2001, to smaller ones on soft targets has forced law enforcement to become more adept at how to prevent and respond to terrorism, said Karen Greenberg, director of Fordham Law School’s Center on National Security.
Safety adjustments made by organizers of the New York City Marathon after the bombing of the Boston Marathon in 2013 — such as banning backpacks and costumes — remain in place, said Chris Weiller, spokesman for New York Road Runners.
Despite widespread news reports and images of the trail of bodies left by the truck attack, the cancellation rate has remained about the same, he said.
Boston Marathon organizers, working with local, state and federal law enforcement, also significantly enhanced security along the course after the 2013 attack, including more officers deployed on race day, a no-fly zone over the course and drones to help with surveillance.
