KANEOHE, Hawaii -- Teens looking to hook up with a friend on the popular Web site MySpace may bump into an unexpected buddy: the U.S. Marine Corps. So far, more than 12,000 Web surfers have signed on as friends of the Corps in response to the latest military recruiting tactic.

MySpace.com, the Internet's most popular social networking site with over 94 million registered users, has helped redefine the way a generation communicates. Users, many in their teens and 20s, post personal profiles and accumulate lists of friends and contacts with common interests.

The Marine Corps set up its own MySpace profile in February to reach a new generation of potential recruits. The Army, which originally balked at advertising on MySpace because of well-publicized incidents of child predators using the site to meet kids, plans to soon set up its own profile page.

"That's definitely the new wave," said Gunnery Sgt. Brian Lancioni at a Hawaii recruiting event. "Everything's technical with these kids, and the Internet is a great way to show what the Marine Corps has to offer."

The Marine Corps MySpace profile -- featuring streaming video of barking drill sergeants, fresh recruits enduring boot camp and Marines storming beaches -- underscores the growing importance of the Internet to advertisers as a medium for reaching America's youth.

But it also highlights the limitations of cyberspace.

Recruiters say MySpace is good for advertising, but they would never sign someone up to join the Marine Corps unless they've met him or her in an old-fashioned, face-to-face meeting.

Patrick Baldwin, an 18-year-old recruit from Saratoga, New York, who linked his profile to the Marines' site after hearing about it from a friend, said MySpace was a good place for interested teens to start learning more about the Marines.

"The more information you have the better off you are," said Mr. Baldwin, who left for boot camp a few weeks ago.

MySpace has rapidly become the online social forum of choice for many in their teens and 20s who like how easy it is to communicate with friends and their friends' friends via the site.

Those with similar interests can join groups and swap ideas on bulletin boards specializing in everything from cars to religion to fashion and the military.

But MySpace also has had some problems.

In Kansas, teenagers hatched a plot over MySpace to bomb a high school. In Maine, a 27-year-old man was sentenced to three years in prison for sexually abusing a 14-year-old girl he met through MySpace.

Last month, the mother of another 14-year-old sued MySpace and News Corp. -- the parent company of MySpace -- in a Texas court for $30 million after her daughter was sexually assaulted by a 19-year-old she met through MySpace.

To boost the site's safety, MySpace recently imposed restrictions on how adults may contact younger users. Those who are 18 and over can no longer request to be on a 14- or 15-year-old's list of friends unless they already know either the youth's e-mail address or full name.

The people who set up the Marine Corps MySpace profile -- the Marine Corps Recruiting Command at Quantico, Virginia -- are not trying to sign up prospective recruits online.

Instead, they want MySpace users interested in the Marine Corps -- especially 17-to-24-year old males -- to reach out to the Marines first.

Web surfers who open the Marines' MySpace page can click on a tab titled "Contact a Recruiter." This directs them to the Marines.com site where they are prompted to fill out a form with their name, address and phone number so recruiters can arrange to meet them in person.

So far over 430 people have asked to contact a Marine recruiter through the site in the five months since the page went up, including some 170 who are considered "leads," or prospective Marine recruits.

The Marine Corps isn't the first to use MySpace profiles to reach the Web community's core audience of teenagers and twentysomethings.

Toyota Motor Corp. has a page to promote the Yaris, its new subcompact car. Verizon Wireless sponsored a contest on MySpace for the best single by an unsigned band.

Louise Eaton, media and web chief for the U.S. Army Accession Command, said the Army decided this month to put up its own MySpace profile.

"It is where prospects are," said Ms. Eaton. "We go to where they are to try to inform them of the opportunities we offer."

The Army initially posted ads on MySpace in January but withdrew them a month later when reports emerged about child predators approaching youths via the site.

MySpace has since assured the Army it has better security protections in place, Ms. Eaton said.

The Air Force Recruiting Service places regular advertisements on MySpace, but doesn't have a profile. The Navy hasn't used MySpace.

Steve Morse with the Central Committee for Conscientious Objectors is critical of military recruiter MySpace profiles. But Morse said they don't surprise him because the Iraq war has forced the military to search "under every bush" for recruits.

"It's kind of obnoxious of them to be using something that's sort of like a youth domain, to kind of come in and really sucker youth into something they're not really explaining fully," Mr. Morse said.

He accused recruiters of drawing people to the military with talk of job training and college money while glossing over the realities of war.

Marine Corps recruiters say they make sure the people they enlist want to be Marines and are right for the job.

They add they're only following their target audience by going to MySpace -- just like they've advertised in newspapers, on television, and on other Web sites.

"As the world changes, so must the United States Marine Corps," said Staff Sgt. J.D. Cress, spokesman for 12th Marine Corps District recruiting headquarters in San Diego.