Although the United States has yet to say officially who it believes was behind Tuesday's terrorist attacks, intelligence analysts and public figures say all indications point to Saudi-exile Osama bin Laden.
Congressman Dan Miller - who traveled with President Bush Tuesday (on Air Force One) - told Reuters news agency the White House is almost certain bin Laden is the prime suspect.
The Republican Representative from (the state of) Florida said the suspicion was based on the level of sophistication and planning needed to hijack four planes and hit targets in two cities within a very short time.
Earlier, a U-S senator said American intelligence had intercepted communications between bin Laden supporters as they discussed the attacks.
U-S officials also said the list of passengers aboard the hijacked planes include the names of suspects linked to bin Laden - the Afghanistan-based accused terrorist mastermind.
British, German, French and Israeli secret services said Wednesday they also believe bin Laden was behind the attacks.
Meanwhile, the Washington Post (newspaper) reports Afghanistan's Taleban rulers have sent their top leader into hiding and are repositioning their military hardware throughout the country for fear of an imminent U-S retaliatory attack.
The report cited Pakistani intelligence sources as saying the Taleban's supreme leader Mullah Mohammad Omar has left his headquarters in the southern city of Kandahar and gone in hiding.
Pakistan is one of only three countries that recognize Afghanistan's Taleban rulers, who have been providing a safe heaven for bin Laden for the past five years.
The Taleban denies that bin Laden could have been involved in Tuesday's attacks in the United States, saying that he does not have access to communication facilities needed to coordinate those attacks.