US national security adviser Stephen Hadley argued the War on Terror could present a "difficult dilemma" and the US administration was duty-bound to protect the American people.
His comment on Sunday came amid heated national debate on whether the CIA and other US intelligence agencies should be authorised to use tough interrogation techniques to extract from terrorism suspects information that may help prevent future assaults.
The US Senate voted 90-9 early last month to attach an amendment to a defence spending bill that would prohibit "cruel, inhuman or degrading" treatment of detainees in US custody.
But the White House has threatened to veto the measure authored by Republican Senator John McCain and has lobbied senators to have the language removed or modified to allow an exemption for the Central Intelligence Agency.
During a trip to Panama earlier this month, President George Bush said Americans "do not torture".
Amending the policy
However, appearing on CNN's Late Edition programme, Hadley elaborated on the policy, making clear the White House could envisage circumstances, in which the broad pledge not to torture might not apply.
"The president has said that we are going to do whatever we do in accordance with the law," the national security adviser said.
"But ... you see the dilemma. What happens if on September 7th of 2001, we had gotten one of the hijackers and based on information associated with that arrest, believed that within four days, there's going to be a devastating attack on the United States?"
President Bush said the US does
not engage in torture
He insisted that it was "a difficult dilemma to know what to do in that circumstance to both discharge our responsibility to protect the American people from terrorist attack, and follow the president's guidance of staying within the confines of law".
Hadley also pointed to the possibility of a compromise with the Senate on the McCain amendment, saying the White House was holding consultations with congressional leaders about the issue.
He hoped lawmakers would be able to come up "with some kind of a common approach that will allow us to both safeguard the country and deal with the president's guidance that we do not torture".