RIYADH, Saudi Arabia, April 27 — Saudi security officials said Friday that they had broken up a vast terrorist ring, arresting 172 men who planned to blow up oil installations, attack public officials and military posts, and storm a prison to free terrorist suspects.
The wide-ranging plot was uncovered over seven months, officials said, as one lead yielded another, allowing authorities to seize a cache of weapons buried in the desert and more than $5.3 million in cash.
The government referred to the ring as a “deviant group,” the phrase often used to describe the ideology of Al Qaeda.
“This did not happen overnight,” said Gen. Mansour al-Turki, a spokesman for the Interior Ministry. “This gives you the idea that terrorists are still trying to re-establish the activities in the kingdom. It is still a war going on.”
Officials said that the suspects had trained abroad, in Somalia, Afghanistan and especially Iraq. The chaos in Iraq has fueled radical ideology among the region’s youth, while providing an environment for militants to train, analysts here said.
“It is the beginning of jihadi operations leaking out of Iraq,” said Abdul Aziz al-Qassim, a retired Saudi judge and moderate Islamic activist. “It is clear that this is some of the effects of what is happening in Iraq, in terms of training and in terms of learning from the Iraqi experience.”
An Interior Ministry statement said there were seven cells scattered around the country, comprising mostly Saudi nationals. Some suspects had begun training to use weapons and others had been sent abroad to learn to pilot aircraft, though the authorities did not say what, specifically, the pilot training was intended for.
It also said that some weapons had been stored near targets and that one group was on the verge of launching its attacks.
In images broadcast on state television, investigators were shown digging up arms in the desert, including plastic explosives, handguns and rifles wrapped in plastic sheeting.
“One of their main targets was to carry out suicide attacks against public figures and oil installations and to target military bases inside and outside,” the statement said.
In Washington, American intelligence officials said it appeared that the Saudis had disrupted a plot by Al Qaeda. One intelligence official said the plot was “well beyond aspirational,” but declined to say how close the militants were to beginning the operation.
General Turki said the investigation was an continuing operation in the kingdom’s battle against an entrenched ideology that promotes terrorism and seeks to recruit young people. The official statement repeatedly referred to “takfir ideology,” a view that effectively allows one Muslim to declare another Muslim an apostate, or nonbeliever, and then kill him.
“We have never actually said we have reached an end,” General Turki said in an interview. “We always confirm that security forces’ efforts are not enough. Not unless you really tackle the ideology that is inspiring these people in order to be involved in these activities.”
The Saudi leadership was forced to address the rise of radical, violent Islamic thinking within its borders after the 9/11 attacks, where 15 of the 19 hijackers were Saudi.
But the kingdom has had its own history of violence and at one time — after the seizure of the Grand Mosque in Mecca by militants in 1979 — found security in supporting some of the most radical Sunni Muslim religious voices. At the time, Saudi officials were also concerned about the Islamic revolution in Iran, which brought a Shiite government to power.
But in recent years, the ideology promoted by Al Qaeda has called for bringing down the royal family, saying it is un-Islamic. Security was stepped up markedly here after the American Consulate in Jidda was attacked and a housing complex for foreigners was bombed.
In recent months there has been a failed attempt to blow up an oil installation, the murder of three French citizens and the beheading of a state security officer, all actions that the authorities here link to the struggle with the most radical ideology. Officials have decided that in addition to relying on the security forces, they will try to “re-educate” those suspected of terrorist links.
The approach has led to a joke going around Riyadh that says the best way to get a job and a new house is to join Al Qaeda — and then repent to the government. General Turki said that when officials change the minds of those caught, the prisoners also end up as useful informers.
“If they change their view, they work against the ideology, they help you, they tell you things,” he said. “They tell you how you can improve your actions to prevent the continuation of the ideology.”
The case announced Friday showed just how much of a challenge the government faced. The number of people was large, officials acknowledged, and came just six months after another 136 people were arrested in a similar sweep and charged with plotting similar crimes, the general said.
“The fact that these young men were recruited points to a huge failure in fighting Al Qaeda,” said Faris bin Hizam, a writer specializing in Al Qaeda. “Fighting Al Qaeda involves a security side and an ideological side. The security side is successful, but the other side of combating Al Qaeda is ideological and it is not successful.”
The announcement of the plot was made Friday, the day of prayer and rest, when all offices are closed. What was most unnerving to some was the government’s description of one of the cells: Officials said it was made up of 61 men, mostly Saudis, who had traveled with their leader to Islam’s holiest site, in Mecca, where they promised “to listen, obey and execute all his orders.”
“Al Qaeda is no longer an organized structure,” said Mr. Qassim, the retired judge. “It became an ideology and a system of work. This is Al Qaeda now.”
Mona el-Naggar contributed reporting.