New York, New Jersey and Washington, DC were placed on a state of highest alert as American authorities prepared for an imminent Al Qaeda attack.
 
Across the Atlantic, American banks, companies and other institutions were also placed under increased security.

Both the American and British governments were responding to information obtained from computers owned by Al Qaeda operatives arrested in an undisclosed destination and Pakistan last month.

One of the men, Ahmed Khalfan Ghailani, a Tanzanian, was one of the Federal Bureau of Investigation's most wanted. He was arrested after a gun battle in Pakistan's Gujrat province on July 26.
 
The other man, Mohammad Naeem Noor Khan, is a Pakistani national and reportedly the son of a Pakistan International Airlines executive. He often traveled to Britain, Germany and the US. He was arrested on July 13 -- presumably in Europe -- for carrying a fake passport.

But The New York Times said much of the information was 'three or four years old.' The newspaper said US intelligence officials said 'they had not yet found concrete evidence that a terrorist plot or preparatory surveillance operations were still underway.'

However, the New York Times said, the officials were concerned that Al Qaeda has enough information to conduct strikes in New York City, Washington, DC and Newark in New Jersey state.

Al Qaeda, the intelligence officials told the newspaper, 'often struck years after its operatives began surveillance of an intended target.'

A former senior CIA official was quoted in London's The Guardian newspaper as saying that information of the attacks also came from MI6, the British intelligence agency, which had interrogated a third Al Qaeda suspect. It is not clear who this man is .

The breakthrough in the case came with Khan's arrest, according to the Guardian. The newspaper reported that 'he led US and Pakistani agents to Ghailani and to Ghailani's laptop, on which a plan for an attack in the US had been downloaded.'

Khan, who was educated at Karachi University, passed on encrypted orders from Osama bin Laden and other Al Qaeda leaders to its operatives in America and Britain. He eluded suspicion on his travels, presumably because he did not apparently fit the profile of the standard Islamic terrorist. He was personable and spoke with what one British newspaper called 'a flawless English accent.'

Khan and Ghailani's laptops contained extensive information on the construction of buildings like the New York Stock Exchange and the World Bank in Washington, DC, 'floor plans of meeting rooms, the configuration of parking garages and even the incline of underground entrances.'

American and British intelligence were shocked to discover the amount of detail -- 'traffic patterns, possible escape routes and details about security guards (their number, shift changes and whether they are armed) as well as discussions about what kind of explosive could do most damage to each of the buildings mentioned,' London's The Times said.