Search efforts in Saudi Arabia continued Monday for American Paul Johnson, who was believed kidnapped several days ago in the capital, Riyadh.

The al-Qaida terrorist group claimed it abducted the defense engineer to avenge U.S. mistreatment of prisoners in Iraq and at Guantanamo Bay in Cuba.

A day earlier the militants also claimed to have shot and killed another American in the Saudi capital, the third killing of a Westerner in Riyadh in a week.

U.S. officials have said the killing of foreigners in Saudi Arabia is a direct attack against the Saudi government. Secretary of State Colin Powell has called on Riyadh to build up Saudi Arabia's security forces and to cut off funding for militant groups.

The head of public affairs at the U.S. mission in Riyadh, Carol Kalin, says that while Saudi Arabia is making every effort to increase security, it is widely believed the fight against the terrorists may prove to be a years-long battle and that consequently, Americans are being urged to leave the country.

"We know the Saudis are doing everything they can to protect Americans living and working here, as well as other foreigners," she said. "We have urged Americans to depart. We think this is a long-term battle that has to go on. Certainly, it does not seem to be a matter of weeks or months at this point in time. We think that, for the moment, it is a dangerous place to live and work."

The violence continues despite a visible increase of security throughout the Saudi kingdom, according to Arab Times journalist Mahmud Ahmed in Jeddah.

"We see it every day in secret police, in heavy presence of security police now," he said. "If you go around Jeddah, where I am staying, compounds are surrounded by police and protected by cement bars. No one goes inside or outside unless he is a resident inside these compounds."

Mr. Ahmed agrees that the battle against al-Qaida terrorists in Saudi Arabia could last for years. But he believes security forces will prevail, which is a belief shared by the spokesman for the 22-member Arab League, Hossam Zaki. He says the entire region has had its past experiences with terrorist groups.

"What we are witnessing is reminiscent of what happened in some other Arab countries ... what happened in Egypt during the 1990s, [with] groups of people who are extreme in their thoughts and who are violent in their means and have absolutely no ethical code," said Mr. Zaki. "And, they behave in a way that seems to be targeting financial institutions of the Saudi state just as some of them tried to undermine the Egyptian economy by targeting tourism during the '90s. And, I predict, very clearly, that just as those who tried to do this in Egypt during the '90s failed, those who are trying to do this in Saudi Arabia will also fail."