After a summer of silence, Al Qaeda leaders are back on the Mideast air waves, framing their latest anti-American message around a possible war with Iraq.

Experts say the terrorist network is on a renewed public relations campaign aimed at keeping itself in the public eye and associated with events which could turn the Arab public against the United States.

U.S. counterterrorism officials believe the tapes -- coinciding with the one-year anniversary of the war in Afghanistan -- are a sign of Al Qaeda's leadership asserting it is still viable to its rank-and-file followers.

The recent taped statements prompted the FBI to issue a new warning to state and local law enforcement agencies that a new Al Qaeda attack on the United States has been approved by the terror network's leadership. But the agency said it did not have any specific information detailing where and when an attack may occur.

On Thursday, the State Department followed suit, issuing a worldwide caution to Americans abroad to alert them to "the continuing threat of terrorist actions that may target civilians."

Last month, the al-Jazeera network aired voice recordings of Usama bin Laden and top Al Qaeda operatives. The CIA authenticated bin Laden's voice, but officials said the recordings probably weren't made recently.

U.S. officials have not verified bin Laden's whereabouts this year and say a previously aired videotape of him having dinner with his associates in early November in Afghanistan is the last absolutely certain sign he was alive.

Those thought to be alive because of their recent recordings include bin Laden's No. 2, Ayman al-Zawahri, and his spokesman Sulaiman Abu Ghaith.

A U.S. official said this week that a recent recording from al-Zawahri appears to be genuine and made in the last few weeks.

The recording, obtained by Associated Press Television News, was produced by a shadowy production company behind previous Al Qaeda videotape. But the format of the al-Zawahri recording is entirely different from the videos released in April which were crude, 30-minute compilations of violent images strung together with Quranic verses and old footage of bin Laden.

The latest disc features snapshots of al-Zawahri and news footage of anti-American protests while he is heard answering an interviewer's questions about America's aims in the region and its future.

The interview runs for a brief five minutes and ends abruptly with the juxtaposition of two images: the collapse of the World Trade Center and Israeli bulldozers destroying a Palestinian home.

Speaking about Iraq, he accused Washington of seeking to subjugate the Arab world on behalf of Israel -- America's strongest supporter in the region.

"The campaign against Iraq has aims that go beyond Iraq into the Arab Islamic world," al-Zawahri is heard saying. "Its first aim is to destroy any effective military force in the proximity of Israel. Its second aim is to consolidate the supremacy of Israel."

State Department spokesman Richard Boucher said the United States continued to receive "credible indications that extremist groups and individuals are planning additional terrorist attacks against U.S. interests."

Of the latest recording, Boucher said: "There is always concern about the potential for attacks, and particularly when Al Qaeda puts out statements one has to make sure that we're appropriately vigilant, not only here but also at our missions overseas."

Mohammed Salah, an Egyptian journalist who covers militant movements for the respected Arab daily Al-Hayat, said the tape was an attempt to piggyback on to world events and drive them in the direction of holy war.

"They are trying to convince people that their cause also includes fighting for the Iraqis and that this is the only way to keep Americans out of the region."

At the same time, Salah said, the organization "is trying to tell the world that they are still strong, that they are a network that is everywhere, not an army that can be conquered."

Al-Zawahri used his time in the interview to assure followers that both bin Laden and Mullah Omar, the former Taliban ruler, were alive and in good health. The Egyptian doctor, who has been bin Laden's spiritual adviser, also warned of future attacks against the U.S. economy and America's allies.

The last series of Al Qaeda messages were publicly released in April, focusing primarily on the Israeli-Palestinian conflict at time when it had reached a boiling point and the death toll was soaring.

A lone audiotape surfaced in June when Al-Jazeera aired a recording of bin Laden's spokesman, who said the Al Qaeda leader and al-Zawahri were alive and that the organization was responsible for a deadly explosion at a synagogue in Tunisia two months earlier.

Michael Swetnam, a counterterrorism specialist at the Washington-based Potomac Institute for Policy Studies and the author of a book on Al Qaeda, said the organization is feeling pressed to keep its image alive even while senior operatives are forced to lay low as the intelligence community cracks down on terror suspects in the United States and Europe.

After a brief lull, Swetnam said, al-Zawahri and others are eager to communicate with senior leaders and entice new recruits with fresh rhetoric.

"This was a message to the cells in Europe that the leadership knows they've been under great pressure but they're still there for them. By issuing these types of releases, (Al Qaeda) can send messages that the leadership is still strong, the war is still on."

But U.S. counterterrorism officials note that while audio recordings are easier to make, they may not have the same impact on followers as video tapes.

Some have speculated that the lack of recent video recordings could mean that al-Zawahri is injured, has significantly altered his appearance, or is in a vulnerable location that could be given away in a video appearance.

A senior Al Qaeda fugitive wanted in the Sept. 11 attacks was captured days after Al-Jazeera aired an audio interview with him.

But Swetnam said the silence and mystery were part of what Al Qaeda is all about.

"Their modus operandi is to plan major events quietly in the background for several years and I think that's what they're up to."