And what evidence would that be?
Officials said that when Al Muhajir arrived in Chicago, he declared having $8,000 but was found to have more than $10,000 in his possession.
In the weeks before he flew to Chicago, Al Muhajir was tracked flying between Pakistan, Egypt and Switzerland, officials said.
U.S. officials later said an "associate" of Al Muhajir had been arrested in Pakistan before May 8. It was not clear whether this was the "associate" Ashcroft referred to when he said Al Muhajir was working with someone in Pakistan on plans to build a dirty bomb." --CNN
...And, I suspect it goes deeper. Naturally, this is based only on what I know. Yet even by that little, I'm satisfied.