Al Qaeda threatened faster, harder strikes against the United States and Israel in a statement attributed to the group that appeared on a militant Web site Sunday.
"The Jewish Crusader coalition will not be safe anywhere from the fighters' attacks," the audio statement said, using a term common among Islamic militants for what they see as a U.S.-Israeli alliance.
"We will hit the most vital centers and we will strike against its strategic operations with all possible means."
The statement was attributed to Al Qaeda spokesman Sulaiman Abu Ghaith. The site, which has posted previous statements attributed to the terror network, included what appeared to be a photograph taken from a video frame of Abu Ghaith.
The Web site also posted a text version of the statement.
The pan-Arab satellite station Al-Jazeera broadcast parts of the audio version and said the voice sounded similar to that on past Al Qaeda videotapes featuring Abu Ghaith.
In Washington, a White House official, speaking on condition of anonymity, said the Al Qaeda statement amounted to no more than a "same song, different day" threat.
The whereabouts of Abu Ghaith, along with Al Qaeda leader Usama bin Laden, have been a mystery since the terror network was chased out of its haven in Afghanistan by U.S. bombing following the Sept. 11 attacks.
"We will chase the enemy using the weapon of 'terror' by widening fighting fronts and conducting more concentrated and faster operations ... so [the enemy] feels unsafe and unstable on land, air and sea," the statement said.
The statement also said a purported Al Qaeda claim of responsibility for the Nov. 28 attacks on Israel targets in Kenya was genuine. That claim was posted on several other Islamic sites last week.
The attacks in Kenya included a hotel bombing that killed 10 Kenyans, three Israelis and the bombers, and a botched attempt to shoot down an Israeli charter plane.
Sunday's statement said Al Qaeda does not usually claim responsibility for attacks but would do so "according to the relevant circumstances."
U.S. officials have said they considered the claim of responsibility for the Kenya attacks to be credible.
Terrorism experts believe Al Qaeda has made use of the Internet, which enables people to communicate cheaply, widely and anonymously. It has been difficult to trace and confirm postings attributed to Al Qaeda that appear periodically on several sites.