LOS ANGELES (CBS) — Police in Los Angeles and across the country went into a heightened state of alert Monday night, the day before the first anniversary of Osama bin Laden’s death.

The FBI and Department of Homeland Security sent out a bulletin warning law enforcement agencies, like LAPD, to be on alert.

One possible threat mentioned was body bombs, where explosive devices are surgically implanted into the bodies of suicide bombers.

“I think we are slightly safer than we were a year ago, but by no means are we out of woods. I think Al Qaeda is still very much a threat to us,” Jere Van Dyke, a terror analyst for CBS and expert on Afghanistan and Pakistan.

While much of Al Qaeda’s core has disappeared, Van Dyke said some of the off shoots remain active, like one in Yemen spearheaded by master bomb maker Ibrahim Hassan al-Asiri, connected with the underwear bomber in 2009 and the failed printer-cartridge attempt in 2010.

New reports suggest that Federal officials are concerned that terrorists are trying to get through airport security by surgically implanting bombs in body cavities.

“I do think that this sort of sophistication, this sort of desire to continue war against the infidel, against the West, against their enemy. I do think, without causing undue fear, is out there and we have to be aware of it, Van Dyke said.

The concept is not new; the film “The Hurt Locker” featured a scene where a bomb is recovered from inside a young boy.

But there are reports Federal marshals have gone overseas before the anniversary to strengthen security on U.S. Airlines.

“We work very closely with the TSA and the FBI and all of the other organizations that are out there. So LAX has always been what we consider one of the targets here in Los Angeles,” said LAPD Cmdr. Blake Chow.

Chow said body scans and increased technology are critical to staying one step ahead. He also said they continue to monitor the Internet surrounding symbolic dates.

“We’re paying more attention tomorrow [Tuesday] to that type of chatter and some of the intelligence that’s coming out, so we and the intelligence community will have our ears very close to the ground, Chow said.

He stressed that there was no specific or credible threat to anything in Los Angeles. But he did urge members of the traveling public to be vigilant and to report anything suspicious.