To protect its citizens, the United States government must turn its attention to threats that could come from outside the country, according to U.S. Secretary of Homeland Security Janet Napolitano.

At a Thursday afternoon town hall meeting organized by the Jackson Institute for Global Affairs, Napolitano spoke to a crowd of about 200 undergraduates and other members of the Yale community gathered in the Law School’s Levinson Auditorium. She emphasized in her talk that government leaders must collaborate with other nations to strengthen homeland security in the United States.

“[Homeland security] is really international in nature,” she said.

Some questions from audience members addressed international security, but dealt mostly with issues of immigration. Lincoln Mitchell ’15 asked about Napolitano’s opinion of Arizona’s new immigration law, which gave law enforcement officials more freedom to demand proof of citizenship from stopped, detained or arrested persons. Napolitano acknowledged that Congress has not proposed a sufficient solution for the nation’s illegal immigration problem, but she said the Arizona law encroached on the federal government’s jurisdiction.

“It is understandable that states are acting … because Congress hasn’t acted,” she said. “Our current immigration law doesn’t match our nation’s needs.”

She added that government officials also need to better enforce policies the United States already has in place.

But in her prepared remarks, Napolitano focused on how nations can work together to promote global security. Countries already have a wealth of information about travel patterns of their citizens, and global security could benefit if they shared this data. For example, many Americans regard the attempted terrorist attack by the “underwear bomber,” who attempted to blow up Northwest Airlines Flight 253 last winter, as a domestic security problem, she said, but the threat originated outside of the United States.

“It was international in nature because once you get into the world’s aviation system, you potentially have access to all of it,” Napolitano said.

While countries already have access to information about their citizens’ travel patterns, no international framework yet exists by which nations can work together to address cyber security threats, she said.

Because many corporations own their digital networks, it can be difficult for the government to regulate them, she said. In response to a question from Jason Toups ’14, Napolitano added that the U.S. Congress, which is currently considering how to protect the United States’ cyber infrastructure without infringing on the rights of individual companies, should provide legal incentives to comply with federal cyber security standards. This “incentive approach” would be more effective than either imposing strict regulations or allowing companies to address the problems themselves, Napolitano said.

“I think you start [with incentives] before you go to a mandate,” Napolitano said. “I would not be confident in the market itself to sufficiently protect [companies].”

Lorella Praeli, a Quinnipiac University graduate who attended the talk as a member of United Action Connecticut, which advocates for civil rights for immigrants, called Napolitano’s solutions “vague” and said she would have liked to hear a clearer plan for implementing immigration policies.

Before being appointed Secretary of Homeland Security, Napolitano was the governor of Arizona from 2003 to 2009 and the attorney general of Arizona from 1999 to 2003.