Barack Obama will be sworn as America's first black president Tuesday under the tightest security ever, shielded by a new, heavily armoured Cadillac limousine, bullet-resistant glass, fighter planes overhead and Secret Service SWAT teams toting automatic weapons.

The president-elect himself will wear bullet-resistant clothing, speak behind a protective glass shield and ride in the inauguration parade in an armoured Cadillac limousine, with doors and windows so thick that he probably would survive a bomb blast, according to law enforcement officials.