Three men, Mohammed Shakil (30), Waheed Ali (23), and Sadeer Saleem (26) have been charged in England "with conspiracy to cause explosions on transport or at tourist attractions" in the 7/7 terrorist attacks. The BBC reports that Scotland Yard says more arrests are expected. This makes sense, of course, because you can't plan, plot and probe for a terrorist attack in a vacuum.

"The allegation is that they were involved in reconnaissance and planning for a plot with those ultimately responsible for the bombings on the 7 July before the plan was finalised," said Sue Hemming, head of the Counter Terrorism Division of the Crown Prosecution Service.

It is well known that the suicide bombers of the 7/7 attack conducted a "dry run," or a test run, of their plot a week before the actual attack. Scotland Yard released CCTV (Closed-circuit television) footage of the four men conducting their dry run on June 28, 2005. Of this video tape, Scotland Yard concluded:

"The obvious implication is that they were conducting a reconnaissance," said Peter Clarke, the deputy assistant commissioner in charge of Scotland Yard's anti-terrorist branch. Mr Clarke said he believed the "dry run" was to check timings and security and that the men were not carrying explosives. 

The new question is, what kind of "reconnaissance" were Mohammed Shakil,  Waheed Ali, and Sadeer Saleem conducting? 

Mohammed Shakil and Waheed Ali were arrested at the Manchester Airport on March 22, 2007 as they were about to board a flight to Pakistan. The third man, Sadeer Saleem, was arrested at a house in Leeds, England. The men have been charged as conspirators in the plot which targeted three London Underground trains and a bus on July 7, 2005. The attacks killed 52 people. These men are the first charged in the plot.