The execution of US journalist James Foley by the Islamic State is “a terrorist attack” against the United States, the White House said Friday, stressing that Washington was considering various options to address the “barbaric murder.”

“When you see somebody killed in such a horrific way, that represents a terrorist attack — that represents a terrorist attack against our country and against an American citizen,” Deputy National Security Advisor Ben Rhodes said during a press conference.

Rhodes did not rule out the possibility that the US would carry out airstrikes in Syria, but stressed that no “specific military option” had been ordered by US President Barack Obama beyond the missions currently taking place in northern Iraq.

Since the US bombing began on August 8, the United States has carried out more than 90 air strikes on IS positions in northern Iraq, particularly around the strategic Mosul Dam, which was retaken Sunday by Kurdish and Iraqi forces.

US Deputy National Security Adviser Ben Rhodes briefs the press at Martha's Vineyard, Massachusetts, on August 22, 2014 (photo credit: AFP/Nicholas Kamm)

US Deputy National Security Adviser Ben Rhodes briefs the press at Martha’s Vineyard, Massachusetts, on August 22, 2014 (photo credit: AFP/Nicholas Kamm)

Rhodes added that Washington was fiercely opposed to the payment of ransoms, saying that countries that responded positively to such requests were mistaken.

“We will not provide funds for terrorist organisms,” he said.

A gruesome video released online Tuesday showing the beheading of Foley by a man who appears to be a British national has sparked international outrage and is fueling fears about the increasing numbers of foreign fighters joining the ranks of the Islamic State

British Prime Minister David Cameron said Tuesday that the man had not been identified but “from what we have seen it looks increasingly likely that he is a British citizen.”

The Guardian quoted sources in Syria saying the executioner had been the main contact for negotiations with families of foreigners held by IS.

Foley, a 40-year-old American freelance journalist kidnapped in Syria in 2012, was shown in an orange jumpsuit kneeling next to a black-clad militant, with a knife to his throat, delivering what is likely a coerced message condemning US strikes on IS targets in Iraq before he is beheaded.

Journalist James Foley in Aleppo, Syria, in November, 2012. The family of the American reporter says he went missing more than one month ago while covering the civil war. (photo credit: AP/Nicole Tung, freejamesfoley.org)

Journalist James Foley in Aleppo, Syria, in November, 2012. (photo credit: Nicole Tung/AP/freejamesfoley.org)

The unidentified Islamic State terrorist who addressed the camera in the five minute video, is believed by linguists to be from London or Southern England based on his accent, which is described as the “multicultural London English” spoken by many young, inner-city residents from a variety of ethnic backgrounds.

Syria’s civil war, in its fourth year, has attracted thousands of foreign fighters from around the world. Several hundred people from Britain have traveled to Syria, according to official estimates, and some may have crossed into Iraq as Islamic State militants advanced. France and Germany have estimated a combined 1,300 of their citizens have joined the fight.

Extremists have increasingly used their foreign-born members for propaganda purposes. In June, the Islamic State released a video showing British and Australian militants exhorting compatriots to join them in violent jihad. Last month, an al-Qaeda-linked group in Syria released a video of an American carrying out a suicide attack.

AP and AFP contributed to this report