The US will not shy away from attacking regimes it considers hostile, or groups it believes have nuclear or chemical weapons, the White House has confirmed.
President Bush has consistently backed the pre-emptive doctrine
In the first restatement of national security strategy since the invasion of Iraq in 2003, the US singles out Iran as the greatest single current danger.
The new policy backs the policy of pre-emptive war first issued in 2002, and criticised since the Iraq war.
But it stresses that the US aims to spread democracy through diplomacy.
The new strategy also highlights a string of other global issues of concern to the US, such as the spread of Aids, the threat of pandemic flu and the prospect of natural and environmental disasters.
National Security Adviser Stephen Hadley is due to make a speech launching the new strategy on Thursday.
Other key points include:
- Stressing US preference for "transformational diplomacy" and coalition building, but not necessarily within United Nations or Nato frameworks
- Criticising the lack of democratic freedoms in Russia and China
- Branding Venezuelan President Hugo Chavez a "demagogue" aiming to destabilise the region
- Urging Palestinian militant group Hamas to recognise Israel, renounce violence and disarm.
The substance of the revised strategy focuses on the challenges facing the US in the wake of the Iraq war.
In a nod to previous high-level foreign policy statements, which singled out individual countries as potential enemies of the US, the new document highlights seven "despotic" states.
They are: North Korea, Iran, Syria, Cuba, Belarus, Burma and Zimbabwe.
The policy of the US, according to the opening words of the 49-page document, is "to seek and support democratic movements and institutions in every nation and culture, with the ultimate goal of ending tyranny in our world".
These motives underpin US policy towards the continuing stand-off over Iran's nuclear programme, the document says.
But it stresses that continuing diplomatic efforts must succeed if confrontation is to be avoided, vowing to take "all necessary measures" to protect US interests against Iran.
The new document, overseen and approved by Mr Bush, leaves the so-called "Bush doctrine" of pre-emptive war largely unchanged.
Iran's president has taken a hard-line position
Before 2002 the US largely focused on the deterrence and containment of unfriendly states.
However, likening the current international situation to the early years of the Cold War, the new document insists on the right of the US to protect its interests using force.
"If necessary, however, under long-standing principles of self-defence, we do not rule out use of force before attacks occur, even if uncertainty remains as to the time and place of the enemy's attack," it says.
"When the consequences of an attack with WMD [weapons of mass destruction] are potentially so devastating, we cannot afford to stand idly by as grave dangers materialise."