The chairman of the U.S. House Committee on Homeland Security said a plot against Pope Francis was disrupted ahead of the pontiff's visit to three U.S. cities. 

Rep. Michael McCaul said the Secret Service told him of the plot during a classified briefing. 

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“The Pope is a very … passionate man. He likes to get out with the people and with that comes a large security risk,” McCaul told Martha Raddatz on ABC’s “This Week.” “We are monitoring very closely threats against the pope as he comes into the United States. We have disrupted one particular case in particular, but as that date approaches, I think we’re all very, being very vigilant to protect him as he comes into the United States.”

Further details about the plot were not available — and it's not clear if the plot was centered on the pontiff's visit to New York, Washington D.C. or Philadelphia.

UPDATE: Yes there will be a fence, and they'll be moving cars for papal visit

McCaul's comments comes amid growing gripes in Philadelphia as to security measures that are being taken to protect the pope — and whether they've gone too far. The city plans to stop drivers from entering a wide area of Center City, and to tow cars from a smaller section. That has left residents wondering how they'll get access to their homes, and businesses wondering how they'll get access to supplies and employees.

Scott White, who teaches security-related topics at Drexel University said that McCaul's statement provide few clues as to the nature of the plot against the pontiff. 

McCaul did not explain how credible the threat was, whether the actors were in the U.S. and whether they had the capability to carry out their plans, White noted. 

He also noted that if arrests had been made, that would likely become public -- so the "disruption" noted by McCaul could mean some other action was taken.

He suspects, however, that this pope presents unique challenges.

"If this is a pope that wants to mingle with the people," McCaul said,  "his vulnerability increases. If he's content to stay behind bullet-proof glass, then his vulnerability decreases."