WASHINGTON, March 16 (Xinhuanet) -- U.S. President George W. Bush on Thursday released second national security strategy report, claiming that Iran may pose the greatest challenge to the United States and reaffirming strike-first policy.

    In the 49-page report, Bush reiterated pre-emptive policy he first outlined in 2002. He said that diplomacy is the U.S. preference in halting the spread of nuclear and other heinous weapons.

    "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," Bush wrote.

    "When the consequences of an attack with weapons of mass destruction are potentially so devastating, we cannot afford to stand idly by as grave dangers materialize. ... The place of pre-emption in our national security strategy remains the same."

    On Iran, Bush said, "We may face no greater challenge from a single country than from Iran. For almost 20 years, the Iranian regime hid many of its key nuclear efforts from the international community, yet the regime continues to claim that it does not seek to develop nuclear weapons."

    "The United States has joined with our European Union partners and Russia to pressure Iran to meet its international obligations and provide objective guarantees that its nuclear program is only for peaceful purposes. This diplomatic effort must succeed if confrontation is to be avoided."

    On the Palestinian Islamic Resistance Movement (Hamas), Bush said, the burden for achieving peace between the Palestinians and Israelis has shifted to Hamas that recently won elections in the Palestinian territories.

    "The opportunity for peace and statehood _ a consistent goal of this administration _ is open if Hamas will abandon its terrorist roots and change its relationship with Israel."

    In the report, Bush also pointed an accusing finger at the Democratic People's Republic of Korea (DPRK). Enditem