Washington: A US man pleaded guilty on Wednesday to providing material support to a US-designated terrorist group and making threats against the writers of the popular "South Park" television show.
Zachary Adam Chesser from Virginia faces a maximum penalty of 30 years in prison upon his sentencing in February, US officials said.
He pleaded "guilty to taking repeated steps in April 2010 to encourage violent jihadists to attack the writers of South Park for their depiction of Mohammed, including highlighting their residence and urging online readers to `pay them a visit,`" the US Justice Department said in a statement.
Chesser, 20, also pleaded guilty to attempting to provide material support to Somalia`s al Qaeda-inspired Shebab Islamists, which the US State Department designates as a foreign terrorist organisation.
In April, the satirical cartoon show "South Park" was censored by the TV channel that hosts it after Chesser -- part of the radical New York-based group Revolution Muslim -- threatened the show`s creators for depicting the Prophet Mohammed.
A spokesman for the Comedy Central television channel said at the time that it added a series of audio bleeps to the episode to effectively remove all references to Mohammed.
Chesser wrote on the Revolution Muslim website that South Park creators Matt Stone and Trey Parker risked the same fate as slain Dutch filmmaker Theo Van Gogh, who was murdered by a Muslim extremist in Amsterdam in 2004.
On its online forum, Revolution Muslim posted the address of Stone and Parker`s Los Angeles production offices, but denied they were encouraging violence, following the April 14 episode of "South Park" where the Muslim prophet appeared wearing a bear mascot costume in order to avoid his image being shown.
On charges of inciting violent attacks within the United States, Chesser admitted that in May this year he posted personal information of individuals who joined the "Everybody Draw Mohammed Day" group on Facebook.
On jihadist websites, he passed on the contact details and wrote: "Just a place to start”.
Chesser twice attempted to travel to Somalia with the aim of joining the Shebab "and engage in violent jihad as a foreign fighter”, officials said. He was arrested in July while making his second attempt to leave the United States for Somalia.
Chesser "seriously endangered the lives of innocent people who will remain at risk for many years to come”, said US Attorney Neil MacBride, noting that once the 20-year-old posted personal information it could be passed on to others to carry out his threats.
"His solicitation of extremists to murder US citizens also caused people throughout the country to fear speaking out -- even in jest -- lest they also be labelled as enemies who deserved to be killed," MacBride added in a statement.
"In admitting his guilt today, Mr Chesser reminded us of the serious threat home-grown jihadists pose to this country."
Chesser admitted that he placed suspicious-looking but innocent packages in public places in an effort to "desensitise law enforcement" about a potential explosive device, according to the Justice Department.
After explaining his actions online, Chesser wrote "Boom! No more kuffar," meaning disbeliever, officials said.
"South Park”, which follows the surreal and often profane adventures of four schoolchildren in a fictitious Colorado town, has regularly lampooned religions during its 13 years on the air.
Cartoon depictions of Mohammed in Scandinavian media outlets in recent years have led to violence and plots to murder those responsible.
In 2005, Danish newspaper Jyllands Posten published 12 drawings focused on Islam, several of which were seen as linking the religion and the prophet to modern terrorism and suicide bombings.
The Danish government refused to apologise for the cartoons -- one of which depicted the Prophet Mohammed with a lit bomb in his turban -- citing freedom of the press. Danish police later said Denmark had become a "priority terrorist target for Islamic extremists”.
The drawings sparked protests in early 2006 that culminated in the torching of Danish diplomatic offices in Damascus and Beirut, a suicide car bomb outside Denmark`s embassy in Pakistan that killed up to eight people, and violent demonstrations that lead to dozens of deaths in Nigeria.