In an article discussing measures that the Fed could take to provide a boost to the economy, the Washington Post tells readers:
"When the Fed was buying $300 billion in Treasurys in mid-2009, part of its try-everything approach to dealing with the crisis, rates on 10-year bonds temporarily spiked amid concerns that the Fed was "monetizing the debt," or printing money to fund budget deficits. With deficit concerns having deepened in the past year, such fears could be even more pronounced now."
The markets don't tell anyone why they moved in a certain direction at a specific time. It is not clear what spike the article is referring to, but the cause of the spike is entirely the interpretation of the Post and should clearly be identified that way. The Post does not really know what caused interest rates to rise, it is presenting its speculation to readers as a fact that is then used to support the case for a more cautious monetary policy.