Washington: The deadly California shooting that killed 14 and injured 17 was a terrorist attack conducted by perpetrators inspired by the Islamic State and possibly linked to Al-Qaeda, according to a top American think tank known for its expertise on terrorists organisations.

"Individuals inspired by the Islamic State (ISIS) and with links to Al-Qaeda conducted the terrorist attack in San Bernardino on December 2," the Institute for the Study of War (ISW) said in a op-ed.