There’s no active threat — but the most likely attack, according to documents, is from “Homegrown Violent Extremists” who sympathize with terrorists overseas but act independently.

Updated at 12:50 PM

The Pennsylvania National Guard is ready to serve during Pope Francis’ visit — to the point of an exercise called “Iron Response,” a late-August training that simulated temporary martial law.

The state Guard and Air National Guard are working with the Pennsylvania Emergency Management Agency on a task force that will support federal agencies in the event of a catastrophe. In such a case, the Department of Homeland Security can declare a state of emergency, which suspends normal civil law. This occurred in New Orleans after Hurricane Katrina.

The task force practiced multiple staged scenarios meant to ready them for the million-plus people expected — but, according to documents reviewed by Billy Penn, its members aren’t sure why. The plans show Iron Responders did not know what their exact role would be.

Maj. Edward Shank, the public affairs officer for the Pennsylvania National Guard, confirmed the training exercise, and said it was a component of the Guard’s annual 2-week summer training.

“It went very well. It was an accident-free training exercise that happened in August,” Shank said. “We gauge it by whether any soldiers got injured. People performed their missions, worked long hours and went home safely to their families after 2 weeks.”

As the Secret Service told reporters last week, there appears to be no specific intelligence indicating an attack during the Pope’s visit. However, the Defense Intelligence Agency assessed the overall terrorism threat level to the continental United States as “significant,” meaning “Anti-U.S. terrorists” are active.

“Concentration of people, international, national, state, and local leaders, and media exposure could make this event an attractive target for terrorist and extremists with a propensity for violence,” reads the Op Iron Response plans. The most likely attack, according to the documents, is from “Homegrown Violent Extremists” who sympathize with terrorists overseas but act independently. “[L]one actors and small groups of violent extremists pose a particular threat because they are already in the country and are more likely to be familiar with prospective targets.”

Shank confirmed that the National Guard will be operating in Philadelphia this week in a supporting role, adding manpower to help officials from the Secret Service to the Pennsylvania State Police with everything from traffic control to handing out bottled water.

According to a medical briefing video that was set to password-protected status after this story appeared, the most likely scenario is a “Mumbai style attack” with small arms and explosives, referring to the four-day-long 2008 assault on the Indian metropolis by ten Pakistani militants. The briefing also warns of possible injury during “crowd control operations.”

Military intelligence is also wary of increased activity of foreign terrorist groups, and cites a recording released in March by the Islamic State of Iraq and the Levant, ISIL, titled “So They Slay and Are Slain,” in which the group’s leader threatens to blow up the White House, Big Ben and the Eiffel Tower in a march to conquer Rome. USA Today reported in February that Vatican authorities were on high alert for an attack via the Mediterranean, after a message from ISIL to the “nation signed with the blood of the cross” warned Italy that the Islamic State was “just south of Rome” in Libya.

National Guard members were told to be wary of infiltration from “Foreign Liaison Officers and suspected Intelligence Officers predominantly active in the state of Pennsylvania,” and likely to “target technologies.” Anyone suspecting they have been contacted by a foreign intelligence agent is instructed to report the incident through the chain of command.

The joint task force is comprised of some 2,000 enlisted personnel who will execute missions related to “Civil Disturbance Ops, Aviation and airspace management,” with a key task of “security and crowd control within the [Area of Operations].” Teams simulated four catastrophic events: An improvised explosive device attack in a backpack, a similar attack from a vehicle, a severe weather incident, and an active shooter/armed attack that might lead to “mass panic (and) trampling.”

The goal was to analyze the potential impacts of such a catastrophe, and to design a plan for operations under a dual-status military-civilian commander who will take charge in its wake, upon approval by the Secretary of Defense. The Air Guard’s orders were to ready two helicopters, a Chinook UH-47 and a Sikorsky Black Hawk UH-60, and one Lockheed-Martin C-130J Super Hercules airplane.

PEMA’s Helicopter Aquatic Response Team conducted its component of the exercise, rescuing victims of a bridge collapse, on the Susquehanna River in Duryea, PA.

The Southeastern Pennsylvania Regional Task Force, a counter-terrorism cooperative that predates the 2001 attack on the World Trade Center, held a Papal Planning Summit with regional emergency management representatives on September 11th in Montgomery County.

The county’s health department is preparing for up to 3 million visitors to Philly this week, but there are still plenty of hotel rooms available and more supply than demand on AirBnb.