WASHINGTON, May 23 (Xinhua) -- The United States said on Wednesday that Iran has not changed its policy on uranium enrichment and vowed not to let Iran develop nuclear weapons.

    "Now, has Iran changed its behavior? No, it hasn't," State Department deputy spokesman Tom Casey said at a briefing.

    The United States believed that through concerted efforts of the international community and through continued pressure on the Iranian government, the Iranian government will have to make a different decision to change its behavior, Casey said.

    Casey said that Iran can have a civilian nuclear power capability that can provide for the needs of its people, but at the same time the international community must be assured that its civilian nuclear program is not used as a cover to build a nuclear weapon.

    Casey made the comments after the International Atomic Energy Agency (IAEA) said in a report on Wednesday that Iran has expanded its uranium enrichment activities in defiance of UN demands to scrap its nuclear-related programs.

    The United States has accused Iran of trying to develop nuclear weapons under the cover of a civilian nuclear program. However, Iran has said its nuclear program is for peaceful purposes only.