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President Obama offered a lawyerly defense of the National Security Agency this morning that can be summarized in two words: Trust us.

"The people involved in America's national security they take this work very seriously," he said. "The last thing they'd be doing is taking programs like this to listen to people's phone calls."

The president, whose administration has been buffeted by a series of disclosures in the last two days about warrantless NSA surveillance, was supposed to be speaking to reporters in the Fairmont Hotel in San Jose, Calif., about health care. But the discussion soon turned to the NSA spy program.

"In the abstract, you can complain about Big Brother and how this is a potential program run amok," Obama said, without discussing details. "But when you actually look at the details, I think we've struck the right balance."

The problem, of course, is that most of the details are classified, meaning Americans don't know the extent of the warrantless spy program. The Guardian newspaper disclosed two days ago that the NSA is vacuuming up millions of domestic phone call records under a secret court order. Then, last night, a pair of reports alleged that Apple, Microsoft, Yahoo, Google, Facebook, and other large tech companies let the NSA peruse confidential user data.

The Electronic Privacy Information Center today said the phone surveillance was illegal and called on Congress to investigate it.