Mr Hamdan's trial is expected to last several weeks
Osama Bin Laden's former driver was so close to al-Qaeda's leaders he knew the target of the fourth hijacked plane on 11 September, prosecutors have alleged.
They were speaking as the first war crimes trial got under way at the US prison in Guantanamo Bay.
Yemeni national Salim Hamdan is accused of conspiracy and supporting terrorism, and faces life in prison if convicted.
He has pleaded not guilty and his defence team say he worked for wages, not to wage war, on America.
Mr Hamdan, who was captured in Afghanistan in November 2001, is the first prisoner to be tried by the US for war crimes since World War II.
Prosecutors told the six-member jury at the military tribunal in Guantanamo that Mr Hamdan was aware of the impending attacks on the US in September 2001.
Navy Lt Cdr Timothy Stone said Mr Hamdan had heard Bin Laden say that the fourth plane was aiming for "the dome", an apparent reference to the Capitol building in Washington DC.
"Virtually no-one knew the intended target but the accused knew," he said.
The plane crashed in a Pennsylvania field as passengers overpowered the hijackers.
"You will not see evidence from the government that the accused ever fired a shot," Lt Cdr Stone told the tribunal.
"But what you will see is testimony regarding the accused's role in al-Qaeda, how he came to be a member of al-Qaeda and how he helped, facilitated and provided material support for that organisation."
The first prosecution witness, a US military officer who was present when Mr Hamdan was captured at a roadblock, said the accused was driving a car that contained two surface-to-air missiles and a piece of paper signed by the leader of the Taleban.
On cross-examination, the officer, identified as Sgt Maj "A" , said he could not be sure Mr Hamdan was the driver of the vehicle.
Legal 'black hole'
Mr Hamdan's lawyers, who unsuccessfully challenged the right of the military tribunal to try him, argued that he was a worker for Bin Laden and did not share the al-Qaeda leader's extremist views.
"He worked for wages - he didn't wage attacks on America," said Harry Schneider, one of the civilian defence lawyers. "He had a job because he had to earn a living, not because he had a jihad against America."
Mr Hamdan has acknowledged working for Bin Laden in Afghanistan from 1997 to 2001 for $200 (£99) a month, but denies being part of al-Qaeda or taking part in any attacks.
The trial judge, Navy Captain Keith Allred, ruled on Monday that some of the statements obtained by interrogators while Mr Hamdan was still in Afghanistan could not be used as evidence.
Mr Hamdan's defence lawyers have argued that the statements were tainted by what have been called "coercive techniques", and he was not advised of his right against self-incrimination.
About 270 suspects remain in detention in Guantanamo Bay.
Among the dozens of other inmates due to be tried there in the coming months are men accused of plotting the 9/11 attacks.
Human rights campaigners have accused the court of operating in a legal black hole and they and the other accused will be watching the proceedings closely, correspondents say.
The verdict will require a two-thirds majority.