Here's some of what I've been able to confirm: Two adult males of Middle Eastern heritage arrived in Las Vegas recently from London during the Islamic observance of Ramadan, the ninth month of the Muslim lunar calendar during which daylight fasting and other religious devotions are observed. During their visit, the men's behavior attracted the attention of JTTF, and around-the-clock surveillance ensued. During that time, the visitors were watched as they visited the Bellagio and Hard Rock Hotel. The visitors also snapped photographs of several Strip properties.

They were followed throughout their stay and out to McCarran International Airport, where they were stopped and consented to be interviewed by investigators. Following the interview, they boarded their flight and returned to London.

Their actions "increased our level of concern," Metro Assistant Sheriff Mike McClary says.

"It is challenging," he adds. "Probably a large percentage of people who come to visit every weekend take pictures."

But independent sources confirm it wasn't just the photography that increased the law enforcement scrutiny. Whether they were simply quirky tourists or genuine persons of interest to anti-terrorist investigators is unclear, and McClary declined to elaborate. What's certain is their actions generated a substantial surveillance effort to ensure their presence here wasn't threatening.

All of this took place with very few members of the public being aware of it. The good times rolled on while in the shadows, the agents and officers did their jobs.

While hard to quantify, it's pretty impressive.

Many millions in counter-terrorism and homeland security funds are being spent to ensure the safety of citizens in major cities across the United States, and it's natural to want to know whether all that money and personnel are being effectively used. They work out of sight and seldom generate headlines.

For some of it, however, authorities believe a higher profile is warranted.

That's what several Strip casino sources noticed recently when they saw a squad of deadly serious Metro officers appear in their midst. McClary confirmed that the department now has two squads assigned to "increase law enforcement presence around critical infrastructure."

Obviously, our great casino machine is an integral part of our economy. It's also a beacon of Western frivolity and hedonistic excess. Since Sept. 11, Strip resorts have been mentioned on terrorist target lists along with Disneyland, the St. Louis Arch, and various Washington monuments. It only makes sense that the casino industry and law enforcement community would be relentlessly vigilant in guarding the American gambling mecca.

That's where the swift-moving, high-profile squads come in. The challenge in the resort corridor: How to show a focused police presence without intimidating tourists. McClary admits it's a balancing act.

"It presents a unique challenge," he says. "We walk a very fine line here."

McClary says the squads were formed and in service before the recent surveillance of the suspicious tourists. Casino sources began reporting their arrival more than one month ago.

The assistant sheriff declined to identify what "critical infrastructure" the squads are monitoring beyond the casino lights. In other metropolitan areas, however, similar JTTF police squads have focused on major transportation facilities such as airports and train and subway stations as well as large utility sites such as power plants and water supply sources.

But it's evident there's also an element of gamesmanship and sleight-of-hand at work. In a business where certainty and irrefutable intelligence are scarce commodities, a sudden police presence is something akin to preventative maintenance.

"The next best thing we can do is throw off somebody's timing," McClary says.

In the end, the two suspicious tourists weren't arrested, but the JTTF did its job and returned to the shadows without interrupting the great Las Vegas party.

John L. Smith's column appears Sunday, Tuesday, Wednesday and Friday. E-mail him at Smith@reviewjournal.com or call (702) 383-0295.