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 is n'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 '' was n'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 .
NSA , FBI and CIA chiefs speak at conference . They discuss cybersecurity efforts , challenges . Private companies urged to safeguard infrastructure .