U.S. Secretary of State Condoleezza Rice says Iran may pose the number one challenge to the United States.
In testimony Thursday before a U.S. Senate committee, Rice cited administration concerns about Iran's nuclear program, its support for terrorism, and belligerent statements from its leaders.
Hours earlier, Iran's Supreme Leader Ayatollah Ali Khamenei said his country will not halt its push for nuclear technology.
Meanwhile, the Bush administration reaffirmed its position it will not seek sanctions in the first stage of United Nations Security Council talks on Iran's nuclear program.
But a White House spokesman Scott McClellan also said U.S. officials will be looking for a "strong" statement from the Council that lays out very clearly for Iranian officials what they need to do. '
On Wednesday, the 35-nation board of the International Atomic Energy Agency reported Iran to the Security Council for restarting its uranium enrichment program.
The Security Council could impose sanctions if it finds that Iran's nuclear activities violate the Nuclear Non-Proliferation Treaty, which the United States and the European Union allege.
In other news, a U.S. State Department official told VOA the international community opposes Iranian attempts to obtain nuclear weapons. But in an interview with the Persian television program "Negahi Faratar", Elizabeth Cheney said no one is trying to deny the Iranian people nuclear energy.
The United States has accused Iran of using its nuclear program as a cover for developing an atomic bomb. Tehran insists its research is for peaceful purposes.