US President George W Bush said he was "not surprised" by threats issued by Al-Qaeda second-in-command Ayman al-Zawahiri to avenge Israel's military assault in Lebanon.
Bush told reporters at the White House late on Thursday that the comments are typical of terrorists who advocate the killing of innocent civilians.
"I'm not surprised that people who use terrorist tactics would start speaking out. It doesn't surprise me," said Bush.
"He (al-Zawahiri) believes that people ought to use terrorist tactics, the killing of innocent people, to achieve his objective," he added.
Al-Zawahiri, an Egyptian believed to be hiding along the Afghanistan-Pakistan border with Osama bin Laden, issued a videotaped statement on Thursday pledging to attack Israelis and their American allies.
In the video broadcast on the Arabic satellite channel al-Jazeera, al-Zawahiri said the latest developments in Gaza and Lebanon constituted a "crusader-Zionist war" against the Muslim world.