U.S. officials are becoming increasingly convinced that Al Qaeda terrorists were behind last week's attacks on an Israeli airliner and an Israeli-owned hotel in Kenya.
Counterterrorism experts have linked the missiles used in the airliner attack to the attempted downing of a military plane in Saudi Arabia last May. Officials also called "credible" a statement posted on an Islamic Web site that said Al Qaeda was behind last Thursday's attacks.
The five-page statement "does appear to be credible," a U.S. official in Washington told Fox News.
The official said the government "can't vouch for the validity of the claim" because Al Qaeda has in the past claimed responsibility for attacks it did not perpetrate. However, U.S. officials "take it seriously."
The claim, posted on the Web site www.azfalrasas.com (Arabic text support required), is attributed to "The Political Office of Al Qaeda Jihad Organization."
The statement called Thursday's attacks in Mombasa — on an airliner and a hotel, both full of Israelis — a Ramadan greeting to the Palestinian people and referred to Al Qaeda's deadly bombings in 1998 against U.S. embassies in Kenya and Tanzania.
"At the same place where the 'Jewish Crusader coalition' was hit four years ago ... here the fighters of Al Qaeda came back once again to strike heavily against that evil coalition. But this time, it was against Jews," the statement said.
"We send [the Jews] a message: Your practices in corrupting earth, occupying sacred places, criminal acts against our families in Palestine," the statement continues. "All your practices will not pass peacefully without firing back. ... Your children for ours, your women for ours, your elders for ours, and we will follow you wherever you are because you made us live in terror and fear."
The attacks were intended to strike fear in travelers, the statement indicated.
"These two operations put thousands of question marks and exclamation points in front of the allied countries that spent millions on programs to protect airplanes from the inside. Here are the fighters attacking them from the outside," it said.
The statement called the U.S.-led war on terrorism "fragile," saying that fighters successfully attacked the hotel in Kenya "at a time when the whole world stands against them, and indeed is hunting them."
In the attacks, two missiles were launched at an Israeli charter airliner just after it took off from Mombasa for Tel Aviv, Israel, with 261 passengers and 10 crew members on board. Both missed. The Arkia Airlines Boeing 757 landed safely at its destination.
About the same time, a vehicle bomb exploded at an Israeli-owned hotel in Mombasa, killing 10 Kenyans, three Israelis and the three bombers. Kenyan officials have detained at least 12 people.
The Internet statement pledged to continue operations, saying, "It is a war between faith and the infidel, between truth and fallacy, between justice and injustice."
Someone listing an address in Dammam, Saudi Arabia, registered the Internet address for the site, which is hosted on computers in Texas, Internet records show.
Two anti-aircraft missile launchers recovered after the failed attack on the Israeli airliner are from the same production batch as one fired in May by an Al Qaeda operative in Saudi Arabia at a U.S. military plane, officials said.
That suggests another Al Qaeda link to the Kenya attacks, because the portable heat-seeking missiles probably were obtained as a group, the officials said.
The U.S. government has obtained other, unspecified information that suggests Usama bin Laden's organization was responsible, they said.
U.S. officials have also suggested an affiliated Islamic extremist network from Somalia, al-Itihaad al-Islamiya, may have played a role.
To make the missile connection, investigators compared serial numbers on the two discarded launchers found with the number on the launch tube recovered outside Prince Sultan Air Base in Saudi Arabia seven months ago. The numbers were close, officials said.
Reuters reported that Kenyan television footage showed that the missile tubes were painted blue, the color of training ordnance used by many militaries around the world, indicating that the missiles may have been both stolen and substandard.
Thousands of this class of missile, known in Western countries as the SA-7 Grail, have been produced in Russia, Eastern Europe, China, Yugoslavia, Egypt and elsewhere. They chase the heat produced by an airplane engine and explode but are effective only while the target plane is flying low and slow.
Weapons inspectors who spoke to Reuters believed that the Israeli charter jet, which would have been less than 500 feet off the ground as it was taking off, must have deployed antimissile decoys, such as flares, to throw off the missiles' homing devices.
A 30-year-old design also known by its Russian name, Strela, or Arrow, these missiles are widely available through illicit arms markets. U.S. officials said they cost $500 to $5,000, while newer shoulder-fired surface-to-air missiles like the SA-14 sell for $10,000 or $20,000.
At least one person who fired the missiles was trained in bin Laden's Afghan camps, and the missiles were smuggled into Kenya from a neighboring country, said sources in Mossad, Israel's intelligence agency, who spoke on condition of anonymity.
In May's failed attempt to shoot down a U.S. military aircraft, captured Sudanese Al Qaeda operative Abu Huzifa acknowledged he fired an SA-7 at the plane flying near Prince Sultan Air Base, where many U.S. forces are based. The incident went undetected until Saudi security forces found the abandoned launcher.
That incident prompted an FBI warning that terrorists may target civilian aviation with missiles. Thursday's events renewed those worries.
President Bush phoned Kenyan President Daniel arap Moi on Monday to offer condolences for the attacks. Moi is to visit Bush at the White House on Thursday; Bush visits Africa next month.
The Associated Press contributed to this report.