Washington, Jan. 20 : Barack Obama''s inaugural ceremony has thrown the biggest challenge so far for the security agencies who have been busy for months ahead of the scheduled swearing-in ceremony to be held on Tuesday, to ensure an incident-free function before the world.

“There have been painstaking preparations, with rehearsals for security officials - not just for the military precision of the ceremony and the parade, stated a British Broadcasting Corporation report on Monday.

At a US military base in Washington they had been planning for any ventuality for the past six months. Huge satellite maps of the centre of Washington dominate the control room at Fort McNair.

They made such arrangements that they should have been in a position to track the new president''s every move - and the huge crowds expected to watch.

They are hoping for the best, but preparing for the worst, the report remarked on Monday.

John F. Kennedy was the last president to be sworn into office without the protection of a bullet proof screen.(ANI)