US police arrested a man near the US Capitol building today after an undercover investigation into an alleged plot to carry out a suicide attack on the national landmark that houses Congress.
"Explosives the suspect allegedly sought to use in connection with the plot had been rendered inoperable by law enforcement and posed no threat to the public," Justice Department spokesman Dean Boyd said.
The officials said the arrest of an illegal immigrant from Morocco capped a lengthy undercover operation in which the suspect had been closely monitored by law enforcement authorities.
The suspect thought he was dealing with members of al-Qaeda, but they were undercover agents, one official said.
When arrested near the Capitol, the man was carrying a vest he thought was packed with explosives, but it was not dangerous, the official said.
There have been a number of undercover operations in the Washington, DC, area in recent years in which suspects thought they were plotting to carry out terrorism attacks but were being monitored by FBI agents and posed no danger.
Officials said the case is expected to be brought by the US Attorney's office in nearby Virginia.
Reuters