David Letterman Beefs Up Security After Jihadist Threat

Days after a jihadist had made violent threats against him, late-night comedian David Letterman tightened security at the Manhattan theater where he tapes his “Late Show.”

A source told the New York Post Friday that additional security precautions were taken at the Ed Sullivan Theater after a Muslim extremist called for Letterman's tongue to be cut out on Shumuka al-Islam forum, a popular Internet destination for radical Muslims.

"Is there not among you a Sayyid Nosair al-Mairi ... to cut the tongue of this lowly Jew and shut it forever?" a user identified as Umar Al-Basrawi wrote, referring to El Sayyid Nosair, who was convicted of the 1990 killing of Jewish Defense League founder Meir Kahane. Letterman is not Jewish.

A law enforcement official who asked to remain anonymous told FoxNews.com on Thursday that while the FBI suspects the post was made by a lone wolf, investigators were scrubbing the site where the threat was posted and conducting database searches to see if the individual was already on their radar.

But a longtime television writer and producer told FOX411.com that he was not surprised at the reaction Letterman received from the extremist community.

“I always say, you cannot reason a man out of a concept that he has not been reasoned into,” Jerry Perzigian told FOX411.

According to Perzigian, Letterman’s team of writers is not likely to back down or censor any of their material in light of the recent threats made against him.

“He milked the Sarah Palin joke for days and the same with his sex scandal,” he said. “Today’s comedians will do anything for a laugh. I’m sure they will relish in it.”

Muslim extremists have targeted several media figures.

Last year, Comedy Central was forced to censor episodes of its show “South Park” after extremists made death threats against the show’s creators Trey Parker and Matt Stone over an episode featuring a cartoon depiction of the prophet Muhammad.

Author Salman Rushdie also spent years in hiding after Iranian leader Ayatollah Ruhollah Khomeini urged he be killed for blasphemy after writing the book "The Satanic Verses."

Filmmaker Theo van Gogh was killed on an Amsterdam street in 2004 by a Dutch Muslim angered by his film "Submission," a fictional study of abused Muslim women.

According to Perzigian, these threats will likely continue and could have an effect on the kind of material that comedians release.

“While political correctness kills comedy, I think people are going to be more and more afraid of radical Islam, more so than other extremist groups,” he said. “These threats are not laughing matters.”

Officials told FoxNews.com Thursday that if there was any reason to believe that the threat would actually be carried out, the FBI would intercede and mitigate the threat.

A rep for Letterman did not respond to request for comment from FOX411.

- FoxNews.com's Jana Winter and The Associated Press contributed to this report.