President Barack Obama''s administration signaled on Thursday that the United States reserved all its options, ranging from diplomacy to military action, to pressure Iran over its nuclear program.

The 10-day-old administration is reviewing U.S. policy toward Tehran, but in a break with the hard-line stance of former President George W. Bush, who branded Iran part of an "axis of evil," Obama has said he is prepared to pursue direct diplomacy with Iran without preconditions.

"We must use all elements of our national power to protect our interests as it relates to Iran. That includes, as the president talked about in the campaign, diplomacy where possible," Obama''s spokesman, Robert Gibbs, said.

"We have many issues to work through -- an illicit nuclear program, the sponsorship of terrorism and the threatening of peace in Israel are just a few of the issues that this president believes the Iranian leadership must address," Gibbs told a White House news conference.

Asked whether Obama''s view was that the military option remained on the table, he said, "The president hasn''t changed his viewpoint that he should preserve all his options."

Bush always insisted that all options, including military action, remained open in dealing with Iran, though he said he was seeking a diplomatic solution.

Iran is engaged in a stand-off with the West over its uranium enrichment program, which it says is for the peaceful generation of electricity but which Western countries fear is a cover to build an atomic weapon.

During his campaign for the presidency, Obama said he would offer Iran various incentives, including helping it to join the World Trade Organization, if it stopped its nuclear work. But he also threatened to step up economic pressure and deepen Iran''s political isolation if it refused.