Pope Francis got an enthusiastic reaction when he spontaneously engaged the crowd with handshakes and hugs on Sunday, but that style might conflict with security considerations, experts say.
"There he was, standing right in front of me reaching out his hand and smiling," said John Bingham, a reporter who got to shake the pope's hand. "It was incredibly different from any pope that I've ever seen at work before."
As the pontiff darted over to the barricades and even went out the gate that opens onto a public street, expressions of concern can be seen on the faces of security officers accompanying him.
"They really looked like they didn't quite know what to make of the situation," said Bingham, who covers religion for the Daily Telegraph in the UK. "I think we saw the car moved five times, just as they desperately tried to work out what he was thinking, what he was going to do."
One Italian newspaper quoted a member of the pope's security detail as saying, if the pope he carries on like this, it will "drive us all crazy."
Andreas Widmer, who protected Pope John Paul II as a member of the Swiss Guard in the 1980s, says a pope has to balance security considerations against his mission of engaging the public and speaking to Catholic audiences around the world.
"The first priority of the papacy is not security. The first priority of the papacy is his ministry," he said. "Having the pope go in St. Peter's Square and things like that -- that's never going to change. That's part and parcel of what he does."
But such openness can be difficult for the people guarding him, a former White House security official said.
"It has to be a nightmare for the security people," said Joe Hagin, who is now with Command Consulting. "Everyone has a different style, and it's security's job to adapt to that style. But I did feel sorry for them."
Vatican spokesman the Rev. Thomas Rosica on Monday expressed confidence in the pope's security team.
"This is something brand new, and they will adapt to that, because they are extremely competent and well-prepared," he said.
Widmer said that based on his experience, the guards are well-trained.
"They know exactly what they are doing," said Widmer. "It's just like a football team: you know what the moves are, where to go, and what to do."
For example, in describing the pope's interaction Sunday, he said, "I think you saw a few times in the video yesterday: as things get crazier, they actually get closer to the pope."
The security of the pope is hardly a new concern. The Swiss Guard began protecting the pope in the 1400s, and in the 1200s, a special passage was built from Vatican City to Castel Sant'Angelo, which served several times as an escape route for popes in danger.
But the near-assassination in 1981 of Pope John Paul II, who was shot four times, prompted security improvements such as bulletproof glass on the popemobile used for public appearances.
Still, John Paul reportedly declined to wear bulletproof vests in public, rejecting the idea as an improper way to avoid Christ's will, according to Bishop Robert Morlino of Madison, Wisconsin. Morlino told the Madison Capital Times that John Paul said his reasoning was this: "I will not die one minute before Jesus Christ wills it, and I will not live one more minute after Jesus Christ wills it."
When the next pope, Benedict XVI, went to Turkey in 2006, there were conflicting reports over whether he would wear a protective vest. But he, too, had the occasional surprises. In 2011, a boy from the audience ran right up to him (he responded with a quick blessing), and on Christmas Eve in 2009, a woman in St. Peter's Basilica jumped over a barricade, eluded a man in a suit who tried to stop her and rushed at Benedict, causing him to fall.
Hagin warns that if Pope Francis develops a predictable routine of meeting with the public, it could pose a security challenge.
"If those who would do him harm know that he is holding a Mass somewhere and know that every time he holds the Mass he goes to the crowd afterwards outside, that would be a problem," he said.
But Widmer says he approves of the new pope's style and says it is up to the guards to adapt to it. Pope Francis, he said, clearly wants to be out among the people.
"He doesn't just shake people's hand; he hugs them, he kisses them," he said. "And that is an expression of the papacy that is just amazing."