WaPo confirms US in dark about plot

They were too busy monitoring the Quakers, Code Pink and Lamont supporters.....

Daily Kos: WaPo confirms US in dark about plot:

At the FBI, several hundred agents and analysts had been assigned to the case beginning in late July, yet only a handful knew about the overall plot or other significant details, according to several law enforcement officials. Many knew nothing about the targets they were watching or investigating, officials said.

So the US intelligence apparatus was in the dark about the London plot - which had been on-going for over a year. OR, they knew about it but were not doing anything about it.
This also means the US and Bush can take little to no credit for thwarting this plot.

Only since the end of July did the FBI start to check phone numbers made by these suspected terrorists. And:
The arrests were carried out as Bush was taking a working vacation at his ranch in Texas. Aides said he and Vice President Cheney had been kept closely informed of developments starting Aug. 4, and were regularly briefed in the days leading to the arrests.