Al-Qaida second-in-command Ayman al-Zawahri warned Americans of a reprisal "far worse than anything they have seen" if Washington did not change its policies toward Muslim states.
"You are facing the Islamic rage ... what awaits you, should you press on (with current policies), is far worse than anything you have seen," Zawahri said in a video posted on the Internet on Wednesday.
Leaders of the militant group which carried out the Sept. 11, 2001 aircraft attacks against U.S. cities often argue that its "terrorism" is justified as a way to change pro-Israel U.S. policies and to punish Washington for its wars in Afghanistan and Iraq.
"I will talk to you in a language you understand; If you want to live safely you have to accept reality and reject the illusions that (U.S. President George W.) Bush is trying to deceive you with," he said in the video.
Part of the video was posted earlier this week on the Web site of the U.S.-based SITE institute.
"You have to try your utmost to reach an understanding with the Muslims, only then you will enjoy security. But if you continue with the policy of Bush and his gang then you won't dream of it," he said.
Zawahri also vowed retaliation against Ethiopian troops for helping the Somalia's interim government rout rival Islamist.
"The Mujahideen will break their backs with God's power and help," Zawahri said.
Ethiopia said on Tuesday its forces began leaving the Somali capital. It has said it does not plan to stay after it completes its mission.
The Egyptian militant also urged Palestinians to abandon President Mahmoud Abbas as a "traitor" and said he had sold his religion and Palestinian land.