Army Gen. Keith Alexander, director of the National Security Agency, told senators that federal data-surveillance programs had prevented dozens of terrorist attacks in recent years, the Wall Street Journal reports. Alexander didn’t elaborate on the attacks that were stopped, other than to tie them to two well-known foiled 2009 plots. He said he would push to make more details available. His comments marked an Obama administration campaign to justify the surveillance programs that include court-approved amassing of phone records of tens of millions of Americans. Those disclosures came from leaks engineered by Edward Snowden, a former NSA contractor who is seeking asylum in Hong Kong. Alexander said NSA goes to great lengths to respect the privacy of American citizens.