WASHINGTON -- The government is encouraging private jet owners and airports to boost security after a message posted in Arabic on a Web forum last week urged Muslims to destroy such aircraft.

The Transportation Security Administration (TSA) issued a security advisory last Thursday that quoted the message as saying, "Destroy private American aircraft ... We call upon all Muslims to follow and identify private civilian American aircrafts in all airports of the world."

The advisory said the posting explained how to identify U.S. airplanes and revealed the tail number of a plane reportedly used by the CIA. It encouraged private jet owners and airport operators to look out for unauthorized or unusual people, cargo and aircraft.

Despite the advisory, TSA spokeswoman Amy von Walter said there is "no specific credible threat."

The TSA and other law-enforcement organizations regularly issue advisories when they have information of a potential threat, though there have been no major incidents since the Sept. 11, 2001 attacks.

"There are so many different threats that are possible. How do you defend against all of them? All you do is take a look at each individual one and how to make it better," said pilot Russ Jones.

The agency said the theft of any private airplane should be reported immediately to the TSA and any suspicious activity should be reported immediately to the TSA and local police.

On The Net: Read TSA's Security Advisory