The Secretary of the Department of Homeland Security told reporters on Friday that the federal government knows of no credible, specific threat to Pope Francis ahead of his visit to the U.S.

"We encourage people to celebrate here in this city," DHS chief Jeh Johnson said. 

Johnson's comments came a few days after the chair of the U.S. House Committee on Homeland Security said that federal authorities had disrupted a plot against Pope Francis. That threat turned out to have been made by a teen from South Jersey who may have had mental health issues, and who may not have had the capability to carry out a plan.

It also comes after months of concern by residents and businesses in Philadelphia over security and traffic restrictions implemented for the pope's visit. 

While officials have declined to talk about the full scope of the manpower behind the operation, it's clear that the security measures are massive. 

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The Pennsylvania State Police say that 1,100 — nearly one-forth of the 4,600-officer force — will be in the region. 

Major Joseph Reed said the agency has stashed ATV's along major highways in case traffic jams make travel impossible. They also have stocked water and emergency supplies along the route for troopers and stuck motorists.  

At a non-descript warehouse in Northwest Philadelphia, 50 city, state and federal agencies will work to collect and disseminate plans about the pope's movements within the city. It's a list that includes the Philadelphia Police, FEMA, the Department of Energy and U.S. Cybersecurity agencies. 

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Special Agent David Beach of the U.S. Secret Service said that in terms of geographic size, the venue where Pope Francis will appear is the largest secure area the agency has ever managed. He said it's more complex than other major events with national security implications that the agency usually plans for. This one is outside, and it cuts through the heart of a major city. 

Despite the agency's efforts to manage every variable it could, where the pope decided to visit was out of its control.

"We don't pick the venue," Beach said.