The New York skyline is still shrouded by smoke
The United States has moved on to a war footing with President George W Bush promising retaliation for Tuesday's attacks in New York city and Washington.
Mr Bush told the American people to prepare for "a long and sustained campaign", and confirmed that he views Saudi dissident Osama Bin Laden as the main enemy.
"If he thinks he can hide from the United States and our allies, he will be sorely mistaken," the president warned.
Speaking to journalists at the presidential retreat at Camp David, Mr Bush said "a group of barbarians have declared war on the American people".
"Everybody who wears the uniform (should) get ready," he added.
Mr Bush's comments followed a meeting with his top advisers to decide how to respond to a series of suicide hijackings of airliners that crashed into landmarks in New York and Washington.
In New York, more than 5,000 people are now listed as missing or dead after the twin towers of the World Trade Center collapsed. Morale among rescue workers remains high, but no one has been found alive for three days.
Amid fading hopes, officials admit they are now primarily dealing with a clear up operation rather than a rescue mission.
Appropriate force
Saturday's talks - which involved Secretary of State Colin Powell, Defence Secretary Donald Rumsfeld and National Security Adviser Condoleezza Rice - followed the authorisation by Congress of "all necessary and appropriate force" in retaliation for the attacks.
No details of their discussions have been released.
But the first signs of preparation are emerging, as the Pentagon ordered vast quantities of aircraft fuel to be sent to a base in Spain and the Diego Garcia staging post in the Indian ocean.
Mr Bush has already declared a national emergency and authorised the call up of 50,000 reservists.
In other developments:
A man is arrested in New Jersey in connection with the WTC attacks - the second confirmed arrest in the investigation. Afghanistan's ruling Taleban - host to Mr Bin Laden - say they will attack any neighbour that assists the US in striking against their country Pakistan agrees to comply with all United Nations resolutions in combating terrorism after America requests assistance in any military strike against Afghanistan, but Iran refuses Parts of downtown Manhattan reopen for the first time since Tuesday as salvage work continues at the site of the World Trade Center The Empire State Building - now New York's tallest building - reopens, but is closed hours later after a bomb scare Non-American airlines resume flights to the US
'Broad and sustained campaign'
President Bush used his weekly radio address to the nation on Saturday to say the National Security Council was using the weekend to "plan a comprehensive assault on terrorism".
"This is a conflict without battlefields or beachheads, a conflict with opponents who believe they are invisible. Yet they are mistaken," he warned.
"Those who make war against the United States have chosen their own destruction."
Planning for a military option to attack targets in Afghanistan - where Mr Bin Laden's bases are located - is going ahead.
However, officials have cautioned that other groups may also have been involved in Tuesday's attacks.
Homeland defence
The Pentagon has said the first 35,000 reservists to be called up would be for "homeland defence" - to protect US cities.
They will include 13,000 airmen, 10,000 army soldiers, 7,500 marines, 3,000 navy personnel and 2,000 coastguard troops.
A $40bn emergency package has been agreed by Congress - double the amount originally requested by President Bush.
The Senate cut through debate and usual parliamentary procedures to rush the money through.
Half of the fund is expected to go to those directly affected - primarily in New York and the Washington area.
Money has also been earmarked for the costs of the rescue mission, reconstruction and improved security.
But the funds can be used to "counter, investigate or prosecute domestic or international terrorism" and for "supporting national security".
Material witness
The unnamed man detained by the FBI on Friday was arrested as a material witness, New York City Police Commissioner Bernard Kerik told a news conference.
This allows investigators to hold him without charge.
A law enforcement source said he was the same person who was detained a day earlier at Kennedy International Airport after showing a false pilot's licence.
Jersey City police officials said a second unidentified man was taken into custody on Saturday in a joint FBI and police operation.
Earlier in Washington, law enforcement officials
said 25 people who had been or would be
questioned by the FBI are in custody for
possible immigration violations.
-- Anonymous, September 16, 2001