One of the most prominent attendees was Spanish Judge Baltasar Garzon, who specializes in investigations on terrorism, crimes against humanity, and international organized crime.
Garzon is so hated in certain circles of his own country that even in New York he is constantly escorted by at least two and sometimes four security guards.
Speaking in New York about the new threats that have arisen since the end of the Cold War, Judge Garzon said that today's common enemy is more complex and elusive than those that Western security forces faced in the past.
"We have to change some of our perspectives as a result of the threat posed by this new invisible power," Garzon said. "This power has been sometimes represented by terrorists in far-flung scenarios like Iraq, where the civil population is being attacked, while other times it has been represented by the drug trade, by organized crime that threatens governance."
Also speaking at the conference was Charles Frahm, the director of the Counterterrorism Division of the Federal Bureau of Investigation (FBI), New York.
Frahm said that in the past the main threat was perceived as coming from the communists, that is, the Soviet Union.
But after the end of the Cold War, it was the first bombing of the World Trade Center in New York in February 1993, he said, that became a cornerstone, the decisive mark that made it clear terrorists were emerging as a major global foe.
Prior to 11 September 2001, terrorism issues were looked at in most countries as an internal matter. But after the 9/11 terrorist attacks, Frahm said, terrorism emerged as a global, focused enemy.
"[It was] really the first time, certainly in the recent U.S. history that all the government agencies knew what their primary mission was," Frahm said. "As simple as that sounds. Even the Drug Enforcement Administration's No. 1 priority, albeit drugs, was to identify any threat from terrorism."
The establishment of the U.S. Department of Homeland Security in 2002, Frahm said, was a fundamental shift in the priorities for all U.S. law-enforcement agencies.
For the FBI in particular, he said, a major issue has become how to proceed legally in different countries with similar but varying laws against terrorism.
"How do we legally proceed in different countries with similar but varying laws on how to go after terrorists in each other's soil?" Frahm said. "And what was critical, was the need for us [FBI] to share information, not just for own consumption, but for the consumption of other governments, to be able to share information which may help that other government take some action either internally or externally within their apparatus."
Bob Kerrey, a former U.S. senator and a member of the National Commission on Terrorist Attacks Upon the United States (9/11 commission), is currently the president of the New School University in New York.
Kerrey said that to be able to perceive the current geopolitical situation in a relevant historical context one needs not only to remember that the Cold War ended approximately in 1989-91, but that the "digital revolution" began in earnest at the same time.
The advancement of the Internet for all its enormous benefits, he said, also empowered terrorists with advantages they couldn't dream of before.
Kerrey also said that the war on terror poses Western government with the difficult challenge of how to crack down on terrorists without adopting overly brutal methods.
He said that a major alienating factor, even for the sympathizers of the United States, is the aggregate detention policy that Washington has applied since the beginning of the battle.
"We have violated a fundamental principle of democracy and made it difficult to sustain the support necessary to make our work against terrorism effective -- the detention policies in Guantanamo, the detention policies in the United States," Kerrey said. "It doesn't mean that from time to time exceptional moves [don't] have to be made in order to protect people, but when the exception becomes a rule, it undercuts our capacity to help people understand that the most difficult thing in democracy is balancing the rights of the individuals against the need to keep the streets safe."
The panel participants discussed the importance of strictly following the rule of law when dealing with the issues of terrorism even in its most radical forms.
Spanish participants in particular warned that curtailing civil liberties and torturing detainees would undermine public support and, eventually, the rule of law.
World: Four Years Later, No Clear Winners In War On Terror (Part 1)
World: Who Is The Enemy -- And How Is It Changing? (Part 2)
World: Can West Fight Terror And Still Maintain Civil Liberties? (Part 3)
World: Global War On Terror Faces Government With Unique Enemy (Part 4)
For all of RFE/RL's coverage on the global fight against terrorism, visit our War On Terror website.