http://www.washingtonpost.com/wp-dyn/articles/A28192-2003Dec24.html "The U.S. Department of Homeland Security had been meeting with French officials in recent days over concerns about a possible terrorist attack.
One U.S. official, who spoke on condition of anonymity, said the U.S. government had been trying to keep the negotiations with France confidential, "hoping that we would be able to lure some of these people in."
The official said there was some frustration within the Department of Homeland Security that the flights were canceled, thus allowing the word to get out about the security concerns."
BTW, these were apparently not flights in which take-offs were imminent and they were cancelled at the last minute. These were 6 different flights scheduled for today and tomorrow.
"The flights scheduled for Wednesday and Thursday were called off because of information obtained "in the framework of the French-American fight against terrorism," the French prime minister's office said."
http://www.washingtonpost.com/wp-dyn/articles/A28192-2003Dec24.html