Recently, the FBI revealed that it had arrested a 15-year-old Philadelphia-area boy on charges that he plotted to carry out Islamic State-inspired attacks involving explosives-packed pressure cookers (in the style of those used in the Boston Marathon attacks.) Although the plot never went beyond Internet chatter, the plan—targeting Pope Francis during his 25-27 September, 2015 visit to Philadelphia—highlights the nightmare that such a significant event can and does have on local, state, and federal law enforcement, the military, and the intelligence community. But just how much of a challenge does such a significant event pose?

To be fair, those whose job it is to protect the Pope and other persons of importance are true professionals and have the dance down pat, so this is in no way a bashing. Pope Francis is, as of the time of this writing, finishing up a visit to Cuba, then he will head to Washington D.C. before stopping in Philadelphia. The Philly visit is the final and largest portion of the 2015 World Meeting of Families (WMF), and according to the website, is “held every three years and sponsored by the Holy See’s Pontifical Council for the Family, the World Meeting of Families is the world’s largest Catholic gathering of families.” The words “world’s largest Catholic gathering of families” are enough to make any security detail leader, police chief, or counterterror operator cringe. (And no, not because they are Catholics, but because of the sheer number of people involved.)

So, for a little background on what Philadelphia and the surrounding areas can expect, let’s put some numbers on the screen (imagine my awesome 2nd lieutenant, up-all-night-to-please-the-general PowerPoint clicking away here). Philadelphia boasts a population of approximately 1,556,600, (according to a 2013 estimate) making it the second largest city on the east coast and the fifth largest in the United States. None of this counts the millions of tourists, business visitors, and other passers-by who trek to the city every week. The city hosts a diverse population, and equally diverse “islands” (those areas within a city—college, financial, ethnic, etc.—where anyone on a surveillance detection route can drag his/her potential followers out of hiding). Everything from the Italian Market to the numerous museums and the Liberty Bell, Philly brings them in droves. And thus the security nightmare is born. Oh, and did I mention that it is being billed as the largest security operation in the U.S. to date? Yeah….

Now, on to some of the physical measures that are already being put in place. And before anyone pulls the “Why are we talking about this? ISIS and OPSEC!” card, cool it. Everything talked about here is public knowledge and can be found if researched. The Ben Franklin Bridge, the main span across the Delaware River that separates Pennsylvania and New Jersey, will be shut down to all vehicular traffic from 10 p.m. Friday night until noon the following Monday. The only traffic allowed on the bridge will be on foot. There will be parking on the Camden, New Jersey side of the bridge, and visitors will be allowed to walk from there into Philly.

To ensure their safety, there will be New Jersey and Pennsylvania state police, as well as local law enforcement, on hand at various intervals along the route, as well as plainclothes officers mixing in with the crowd. According to a friend who works for a local police department, various towns in Pennsylvania and New Jersey have contributed officers for crowd/riot-control details, and they have been and will be on standby for the duration of the visit. Per protocol, the United States Secret Service will head the security operation and will work close-in security for the Pope.

Within the city, security perimeters, which can be viewed here, have been established in order to both screen visitors and control the flow of foot traffic. Eight-foot-high security fences have been set up, and I have been told that about 1,500 bike racks have been brought in to act as barriers as well. Travel into and out of some of the security zones will be strictly monitored, and metal detectors have been put in place. Items such as selfie sticks and balloons (two on a long list) are banned, and bags will be checked. The Ben Franklin Parkway, where the Pope is expected to hold high Mass for an estimated 1.5 million people, has been designated a top priority security zone.

In the year, months, and days leading up to the events of the week, law enforcement, military, and intelligence entities have been sharing information related to the Pope, his visit, and any threats against him. Before the he even left the Vatican, wheels were put into motion to ensure His Holiness’s safety. Our very own Frumentarius, at one time, covered the Vatican City account in the CIA’s Counterterrorism Center, so he knows all too well that threats against the Pope happen every day, noting that overall responsibility for the Pope’s security rests in the hands of the Italians and former intel and Carabinieri officers, who do a great job with limited resources.

FBI and Secret Service agents will be combing their files for anyone who has made even a passing threat against the Pope or the Catholic Church, and will make visits to each person for an interview to determine their threat level. Intelligence agencies will be monitoring daily cable traffic for threat information, and collectors (operations officers, etc.) will be meeting with sources to glean new info or verify what info they have. Closer in, in Washington D.C., New York, and Philadelphia, agencies will be coordinating contingency plans using everything from counter-sniper teams to EOD bomb teams and the Secret Service’s own counter-assault teams.

Many see the security measures as overkill, and to the casual observer it may seem that way. But look at it from the point of view of the Secret Service agent, the FBI agent, or the street cop. Although most look at the news coverage and see all of this being put on for one man, the security personnel on the ground and behind the shadows are taking in the whole picture, knowing that the person who might have been mugged is saved by the undercover cop they never saw, but who saw the threat. They also know that the Pope may not be the target. It could be the stadium in Camden, where thousands will be watching the Mass on Jumbotrons; or the Ben Franklin Bridge, where faithful will be walking across in droves. No doubt the Secret Service is stressed enough at the thought of the “People’s Pope” reaching into the crowds or hopping off of the Pope Mobile (yep, it’s a Fiat) to dine with the homeless (good on him), but they have the comfort of knowing that thousands of others who stand on the wall have their back.