In a recent video American-born Al Qaeda militant Adam Gadahn asked wealthy Muslims to offer cash rewards for the killing of United States and western diplomats around the Muslim world.
The threat comes as many western nations temporarily closed embassies across the Middle East and North Africa earlier in August, after intelligence warned of a possible militant plot in the region.
Gadahn, also known as Azzam the American, praised the murder of former US ambassador to Libya, John Christopher Stevens, and called for the death of his successor, Deborah K. Jones.
"These prizes have a great effect in instilling fear in the hearts of our cowardly enemies," Gadahn said in the 39-minute video posted on Islamist militant websites, according to SITE, a Washington based monitoring group.
"They also encourage hesitant individuals to carry out important and great deeds in the path of Allah," said Gadahn, who, with a $1 million price tag on his head, has called for these kinds of attacks before.
Gadahn has been indicted in the Central District of California for treason and for offering material support to al Qaeda. "The charges are related to Gadahn's alleged involvement in a number of terrorist activities, including providing aid and comfort to Al Qaeda and services for Al Qaeda," according to FBI records.
The offering of bounties is not unsual. Last year al Qaeda in the Arabian peninsula said it would give people gold for the assassination of the US ambassador in Sana'a, or about $23,350 for the murder an American soldier, according to Reuters.