An Internet Web site has posted a video of al Qaida's leader in Iraq, Abu Musab al- Zarqawi, vowing to defeat the United States.
In the video, al-Zarqawi also ridicules Iraq's new government.
The video - believed to be the first to show al-Zarqawi's face - shows a bearded male dressed in black and wearing a military vest. U.S. intelligence officials studying the tape say they believe it is authentic.
The video came two days after the release of an audiotape in which Osama bin Laden accused the West of waging a "crusader-Zionist war" against Muslims.
Meanwhile, Iranian President Mahmoud Ahmadinejad told Iraqi Prime Minister-designate Jawad al-Maliki that the formation of Iraq's unity government will lead to the withdrawal of U.S. forces from the country. Iran's state news agency reported the two men spoke Tuesday by phone.
Mr. Maliki was nominated as prime minister Saturday after Iraq's Shi'ite, Sunni Arab and Kurdish parties settled a four-month deadlock over leadership positions.
In violence Tuesday, police in Baghdad said a bomb killed at least two people when it exploded near the office of radical Shi'ite cleric Moqtada al-Sadr.
Elsewhere in Baghdad, two bomb attacks wounded four police officers. And south of the capital, gunmen killed a school teacher.
Some information for this report was provided by AP.