In response to reports that the National Security Agency had spied on world leaders -- including Germany's Angela Merkel  -- the response from the White House was a now-familiar one: President Obama didn't know about it.

NSA chief Keith Alexander "did not discuss with President Obama in 2010 an alleged foreign intelligence operation involving German Chancellor Merkel, nor has he ever discussed alleged operations involving Chancellor Merkel," said a spokeswoman for the agency. "News reports claiming otherwise are not true."

"Obama didn't know" has become a regular refrain for this White House. Last week, Health and Human Services Secretary Kathleen Sebelius said the president was unaware of the red flags that had been raised in regards the launch of, and back in May the President himself said knew nothing about the reports of the IRS targeting of conservative groups before he read about it in the media.

We talked Monday with Washington Post chief White House correspondent Scott Wilson about the efficacy (or lack thereof) of the "I don't know" strategy and what it might mean for the President.

The White House claims President Obama didn't know about NSA spying on world leaders. Washington Post chief White House correspondent Scott Wilson weighs in on the strategy of keeping the president out of the loop. (The Washington Post)