Intelligence chiefs: Privacy is respected August 9, 2013 -- Updated 0052 GMT (0852 HKT) General Keith B. Alexander (L); John O. Brennan (C); and Robert S. Mueller II (R), take part in a Q&A forum during the International Conference on Cyber Security. NSA, FBI and CIA chiefs speak at conference They discuss cybersecurity efforts, challenges Private companies urged to safeguard infrastructure New York (CNN) -- The leaders of the top three U.S. intelligence agencies made an unusual joint public appearance Thursday to make a pitch for companies to cooperate more with the government in cybersecurity efforts, and defended the work their agencies do amid controversy over vast data mining programs that critics say invade Americans' privacy. National Security Agency Director Gen. Keith Alexander, FBI Director Robert Mueller and CIA Director John Brennan said the government does its best to ensure the work their agencies do is focused on protecting the nation from harm, while respecting privacy. The three appeared at a cybersecurity conference at Fordham University, co-sponsored by the FBI's New York field office. Alexander, whose agency is the focus of pressure following disclosures of secret programs by former NSA contractor Edward Snowden, said his agency is working to address vulnerabilities from insiders, such as computer system administrators. Snowden's work as a system administrator allowed him broad access to the NSA's secrets. Silicon Valley to feds: Disclose your data requests He said the agency was working to reduce system administrators by 90% though he acknowledged it was a difficult goal to reach. Much of what the system administrators do could be done by computers, he said, leaving humans to do the most important work to protect the systems. The conference of corporate and government cybersecurity managers made for a friendly audience, applauding the speakers when they defended the work the government was doing. Alexander won applause when he said the NSA programs have been "grossly mischaracterized in the press" and that the system the U.S. government has come up with, working with the courts and Congress, works better than anywhere else in the world. Report: Microsoft collaborated closely with NSA He cited President Barack Obama's comments on a late night talk show, saying of the controversial NSA programs: "this isn't a domestic spy program" but rather a program to protect the nation from terrorists. The problem for the intelligence agencies, he said, is that terrorists use the same devices and communications methods as other people do. In light of the recent controversy, it's important to know that "No one has willfully or knowingly disobeyed the law," Alexander said. How to hide your data from Internet snoops The word "privacy" wasn't mentioned until the last few minutes of the 90-minute program. When asked whether Americans had any expectation of privacy nowadays, Brennan said, "I do believe privacy is important, but privacy can be defined in different ways." Mueller urged companies to work with law enforcement to help protect crucial infrastructure from cybercriminals, who sometimes are sponsored by foreign state security agencies or criminal syndicates. The three men urged companies to support the Obama administration's effort to pass cybersecurity legislation, an effort that has been sidelined in recent months amid the controversy. Read more: Germany ends information sharing pact with Britain, United States