After a shootout in Riyadh, the Saudi capital, and the discovery of a major arms cache there, Saudi authorities are pursuing 19 Islamic militants with ties to al-Qaeda who now appear to have been planning a substantial terrorist attack, Saudi and US officials said on Friday.
In an indication of how seriously the threat is being taken in Saudi Arabia, the Saudi government has been unusually open in discussing it, even making public the names and photographs of the wanted men in the country's newspapers and television broadcasts this week.
With the militants still at large three days after a raid in Riyadh, Saudi and US officials said they could not or would not say what they thought the target of a planned attack might have been. But they said they regarded the group as having been planning a significant operation whose most likely objective would have been a US target in the Saudi kingdom.
"Tremendous damage could have been done," a senior Saudi official said on Friday of the plot, which was uncovered beginning Tuesday night after a raid on a home in Riyadh. Among the weapons seized were 800 pounds of advanced explosives along with hand grenades, assault rifles, ammunition, disguises and tens of thousands of dollars in cash, the Saudi government has said.
The raid came several days after the State Department, on May 1, issued an extraordinarily specific warning about possible terrorist attacks in the kingdom, saying the US had received intelligence reports indicating that militants "may be in the final phases of planning attacks" on US interests in Saudi Arabia.
In a kingdom whose government has always been extraordinarily reticent, particularly in discussing matters related to the involvement of Saudi citizens in terrorism and domestic dissent, people interviewed from Saudi Arabia on Friday described their astonishment at the public nature of this week's disclosures.
"They are sending the clear signal that there's a clear threat, and they're taking it seriously," said a US official who spoke on condition of anonymity. A Saudi official said the signal was aimed both at the US, where critics have often accused the kingdom of trying to hide its problems, and at ordinary Saudis themselves, some of whom have become impatient with the government's customary secrecy.
While investigators from both countries believe the most likely target was a US installation, a senior Saudi official said, another possibility was an attack aimed at a senior member of the Saudi royal family, like Prince Sultan Abdelaziz, the defense minister, or Prince Nayef bin Abdelaziz, the interior minister, two frequent targets of criticism by Saudi militants.
Among the 19 militants being sought, the Saudi government announced this week, 17 are Saudis, with known connections to al-Qaeda, according to US and Saudi officials.
A senior Saudi official said that most if not all had served in Afghanistan or Chechnya, and had links to radical clerics.
Jamal Khashoggi, who is editor of the Saudi newspaper Al Watan and is an expert on Islamic militants, said in a telephone interview from Jidda on Friday, "It is a big network, it is a serious network, and it is obvious that they were planning for a massive campaign of terrorism."