International diplomatic efforts to persuade Iran to give up its nuclear program must succeed to avoid confrontation, US President George W. Bush said in a national security report yesterday.

"We may face no greater challenge from a single country than from Iran," Bush said in the document.

Diplomatic efforts must succeed "if confrontation is to be avoided," Bush said in the security document.

Seeking to draw a line between the Iranian government and the Iranian people, Bush said Washington's strategy is to "block the threats posed by the regime" while expanding its engagement with the people.

The United States and the European Union (EU), which have said Iran is seeking the capability of making nuclear weapons, are pushing for a full suspension of Iran's nuclear fuel activities.

Tehran insists that its nuclear program is solely aimed at power generation and that it has the right to conduct uranium enrichment.

Bush made clear in the document that Washington does not view the failure to find the weapons of mass destruction in Iraq as a blow to its strategy of preventive war.

Reaffirming the strategy of preventive war and U.S. unilateralism in the security report, Bush said that "we do not rule out the use of force before attacks occur" and that "we must be prepared to act alone if necessary."

The U.S. launched the war against Iraq in 2003 on grounds that then Iraqi President Saddam Hussein had possessed weapons of mass destruction, but no such weapons have been found despite many searches across the country since its occupation.