The cave tucked in the remote Saudi mountains near the Yemeni border was clearly a way station for Islamic militants, Saudi police say, pointing to the stock of guns and ammunition, nooks for holding hostages and cameras for filming them.
It even had buckets of sugar, rice and flour, as well as boxes of charcoal, candles, pasta and beans _ supplies for a long stay by al-Qaida fighters moving across the border to prepare attacks in the kingdom.
The discovery in early April reinforced a growing fear in Saudi Arabia: that Yemen could become another Afghanistan right on its doorstep, an out-of-control state where al-Qaida runs free and exports violence into its neighbor.
The United States shares the Saudis' fear. Gen. David Petraeus, head of the U.S. Central Command, told Congress in April that the weakness of Yemen's government provides al-Qaida a safe haven and that terror groups could "threaten Yemen's neighbors, especially Saudi Arabia and other Gulf states."
Yemen is the Arab world's poorest nation _ and one of its most unstable _ making it fertile territory for al-Qaida to set up camp. The country is also in a strategic location, next door to some of the world's most important oil producing nations. It also lies just across the Gulf of Aden from Somalia, an even more tumultuous nation where the U.S. has said militants from the terror network have been increasing their activity.
Al-Qaida militants, including fighters returning from Afghanistan and Iraq, have established sanctuaries among a number of Yemeni tribes, particularly ones in three provinces bordering Saudi Arabia known as the "triangle of evil" because of the heavy militant presence, Yemeni authorities say.
In January, militants announced the creation of al-Qaida in the Arabian Peninsula, a merger between the terror network's Yemeni and Saudi branches, led by Naser Abdel-Karim al-Wahishi, a Yemeni who was once a close aide to Osama bin Laden. Over the past year, al-Qaida has been blamed for a string of attacks, including an armed assault in September on the U.S. Embassy in San'a, as well as two suicide bombings targeting South Korean visitors in March.
Al-Qaida fighters in the country are believed to number in the low hundreds. But the presence is strong enough that Yemeni President Ali Abdullah Saleh in February pleaded with tribesmen in the "triangle of evil" to turn in militants.
"You are the triangle of good, giving and loyal men. Fight terrorism and don't ignore it," Saleh told tribal members in Mareb province. "Does anyone here want to take us back to square one? To the days of ignorance, poverty and isolation?"
Yemen, the ancestral home of bin Laden's family, has long been an al-Qaida stomping ground. The country was the scene to one of al-Qaida's most dramatic pre-9/11 attacks, the 2000 suicide bombing of the destroyer USS Cole off the Aden coast that killed 17 American sailors.
But the difference now is that rather than just carrying out attacks in Yemen, a new generation of al-Qaida militants appears to be trying to establish a longterm presence here, uniting Yemenis returning from fighting in Iraq and Saudis fleeing the kingdom's crackdown. They have openly declared their aim to overthrow Saleh for his joining Washington's war on terror.
Unlike Afghanistan under the Taliban, al-Qaida doesn't have a government supporting it in Yemen. But it doesn't necessarily need it. Government control is weak over much of the mountainous, desert nation. Many areas are lawless, weapons are plentiful, and rampant poverty _ which is worsening with falling oil prices _ makes recruiting militants easy.
Many tribes are disgruntled with the government, and can be paid to provide havens for militants. Abdul-Karim al-Eryani, a political adviser to Saleh, says that the miltiants seem to be well-funded and that security forces are reluctant to move strongly against them because then "it becomes a war between the state and the tribes, which is not advisable."
Even tribesmen who are not sympathethic to al-Qaida are reluctant to hand over militants because of the traditional custom of generosity toward guests.
Ji'bil al-Deeman, a tribal leader in Mareb _ which along with Shabwa and Jof provinces make up the "triangle of evil" _ says he opposes al-Qaida because its attacks impede badly needed development projects. But if a militant showed up in his territory, al-Deeman said he would just order him out, not alert the police.
"I won't hand him over to authorities. It's shameful to do so to someone who asks for my protection," said al-Deeman. "Anyone who did so would be considered a deficient tribesman and would bring shame to his tribe."
Other tribesmen also deny harboring al-Qaida, and blame the government's failure to address poverty for a rise in militancy behind recent attacks. Yemen, a country of 22 million people more than twice the size of California, has a 35 percent unemployment rate and a 50 percent literacy rate.
"We have a corruption problem in this country, we have a lawlessness problem," said Mufarreh Buhaih, a tribal chief in Mareb. "We worry that this country will turn into another Somalia and become a real sanctuary for terrorism."
At the same time, the government is caught up in other problems _ the possibility of a new flare-up in a Shiite uprising in the north and tensions in the south, where separatist sentiment is mounting.
Even in the capital San'a, where government control is tight, tensions are palpable. Random checkpoints crop up across the city, with troops searching cars and sometimes frisking passengers. Hotels are putting up fences and installing high-tech security devices. New security measures have been imposed at the international airport, even barring friends and family from entering the arrivals terminal to greet imcoming passengers.
The San'a government's weakness has made Washington hesitant to return dozens of Yemenis currently being held at the Guantanamo Bay military prison, which President Barack Obama has promised to shut down. The U.S. apparently fears the freed detainees could come under the sway of al-Qaida. Earlier this month, Obama counterterrorism adviser John Brennan met with Yemen's president and underlined the U.S. concerns, the State Department said.
In January, Saudi Arabia issued a list of its top 85 most wanted militants living abroad, most of them in Yemen, including al-Wahishi, the 33-year-old leader of the merged Yemeni-Saudi al-Qaida.
In the years immediately following the attacks of Sept. 11, 2001, al-Qaida militants tried a direct assault on Saudi Arabia, carrying out a string of shootings and bombings against Saudi police, foreigners and infrastructure. A heavy crackdown largely crushed al-Qaida cells in the kingdom.
Now Saudi Arabia fears al-Qaida is trying again, this time through the backdoor via its southern neighbor.
The cave hideout illustrates the dangers. The border, running 1,300 kilometers (800 miles) through rough desert and mountain terrain, is highly porous. That makes it easy for militants to enter Saudi Arabia or for Saudis to cross into Yemen for a few days militant training, then return home.
In their April raid on the cave, Saudi police seized 11 suspected Saudi militants planning armed robberies, possibly on banks and shops in Saudi Arabia to finance their operations, Saudi Interior Ministry spokesman Brig. Gen. Mansour al-Turki said. The cave included nooks set up apparently to hold hostages and film them for Web videos.
"The cave was a foothold for al-Qaida," said al-Turki. "It could've been used for logistical support, as a shelter or a holding area for infiltrators."
Those arrested at the cave are the most serious cell of militants caught so far in southern Saudi Arabia because of its "ready-to-execute plots, targets and capabilities," al-Turki said.
Al-Qaida, he said, is trying to lure young Saudis to get militant training in Yemen, instead of having to go all the way to Afghanistan.
"The youths can slip over to Yemen for a few days training and return home without raising their parents' suspicion because their absence won't be long," he said.