America will continue to pre-emptively attack its enemies and Iran is now the greatest danger facing the United States, George Bush announced today in a new version of his "National Security Strategy".

In the 49-page document released four days before the third anniversary of the American -led invasion of Iraq, Mr Bush gave a resolute, upbeat account of the ongoing wars in Iraq and Afghanistan and said his Administration would continue to confront states before they had a chance to attack America or develop nuclear weapons.

"Our strong preference and common practice is to address proliferation concerns through international diplomacy, in concert with key allies and regional partners," he wrote.

"If necessary, however, under long-standing principles of self defense, we do not rule out the use of force before attacks occur, even if uncertainty remains as to the time and place of the enemy’s attack."

Mr Bush said that the September 11 attacks had "underscored the danger of allowing threats to linger unresolved", and although he conceded that the intelligence that had led to the war in Iraq was wrong, he insisted that the strategy of attacking threatening nations and groups before they could harm America was valid.

In a broad study of the global security situation, in which Mr Bush identified economic progress and free trade as important catalysts for democracy, the US President singled out Iran as the clearest, present threat to stability.

"We may face no greater challenge from a single country than from Iran," he wrote, after describing the clerical regime in Tehran as an "enemy of freedom, justice, and peace".

Mr Bush accused Iran of masking its nuclear intentions for almost 20 years, wilfully disrupting negotiations with the international community and meddling in Iraq.

"The Iranian regime sponsors terrorism; threatens Israel; seeks to thwart Middle East peace; disrupts democracy in Iraq; and denies the aspirations of its people for freedom," he wrote.

"The nuclear issue and our other concerns can ultimately be resolved only if the Iranian regime makes the strategic decision to change these policies, open up its political system, and afford freedom to its people. This is the ultimate goal of U.S. policy."

Mr Bush's report, an update of a security strategy he wrote in 2002, set the White House's War on Terror in the grand tradition of American foreign policy.

He compared the ideological battle against radical Islam to the Cold War and said the decision to take the fight to the enemy reminded him of decisions made by Ronald Reagan during the 1980s and Harry Truman immediately after the Second World War.

"The path we have chosen is consistent with the great tradition of American foreign policy. Like the policies of Harry Truman and Ronald Reagan, our approach is idealistic about our nation's goals, and realistic about the means to achieve them."

Alongside Iran, Mr Bush identified North Korea and Syria as two other troublesome nations. He accused Kim Jong Il of running a regime in Pyongyang that poses a nuclear threat to the US, starves its people, counterfeits money and traffics drugs. Syria, he wrote, oppressed its people and sponsored terrorism.

Mr Bush said that America was keen to strengthen its relations with Russia and China, its two Cold War adversaries, but rebuked both for their uncertain commitment to democratic reform.

Russia, he complained, was impeding the spread of democracy in the former Soviet Union. "Recent trends regrettably point toward a diminishing commitment to democratic freedoms and institutions," he wrote. "We will work to try to persuade the Russian Government to move forward, not backward, along freedom’s path."

China, for its part, was accused of building up its armed forces "in a non-transparent way" and of pursuing trading relationships with countries with poor human rights records. Mr Bush said China would be forced to offer more freedoms to its people and prosperity increased but that America would be prepared if Beijing continued to deny reform.

"Our strategy seeks to encourage China to make the right strategic choices for its people, while we hedge against other possibilities," he wrote.

Mr Bush's security strategy was published as the American President is bedevilled by the worst approval ratings of his five years in office and calls from his own party to introduce fresh faces to a White House apparently unable to shrug off a series of scandals.

The Bush Administration has also been accused of being shorn of ideas for withdrawing US troops from Iraq. Yesterday, a ten-member panel of foreign policy experts was formed to describe the state of the war after the US Congress said it needed "an honest assessment of where we are and how we go forward and take this out of politics".

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