FBI Warns of Homegrown Violence After Afghan Massacre Federal authorities have issued a warning there could be "acts of violence" in the homeland sparked by the recent massacre of 16 civilians in Afghanistan allegedly by an American soldier. "The FBI and DHS [Department of Homeland Security] are concerned that this event could contribute to the radicalization or mobilization of homegrown violent extremists [HVEs] in the homeland, particularly against U.S.-based military targets which HVEs have historically considered legitimate targets for retaliation in response to past alleged U.S. military actions against civilians overseas," the FBI and DHS said in a joint "awareness bulletin" to law enforcement agencies Wednesday. The bulletin noted that there is no specific threat at this time and said it is "unlikely" the recent killings and other "high-profile perceived offenses against Islam" would motivate any homeland extremist to violent action. "However," the bulletin says, "[the killings] will likely be incorporated into violent extremist propaganda and could contribute to an individual's radicalization to violence." High level federal officials have repeatedly warned that one of the greatest threats facing the American homeland comes from self-radicalized, homegrown terrorists who may be inspired by -- but have little to no contact with -- major terrorist groups. In December, a Congressional report released by the staff of Rep. Peter King, chairman of the House Homeland Security Committee, said such homegrown terrorists were a "severe and emerging threat" to the U.S. military at home and said military communities in the U.S. "have recently become the most sought-after targets of violent Islamist extremists seeking to kill Americans in their homeland." READ: Homegrown Islamic Terror 'Severe' Threat to US Military at Home, Report Says Tensions at home and abroad have been strained since an American soldier was accused of systematically murdering 16 Afghan civilians -- mostly women and children -- in the middle of the night Sunday, apparently in an unprovoked attack in Kandahar. The soldier, identified only as a staff sergeant hailing from Joint Base Lewis-McChord in Washington state, surrendered when he returned to his base in Afghanistan and has since been moved to Kuwait. READ: Afghanistan Killings and the Troubled History of American Base The killings have sparked some heated protests in Afghanistan during which Afghans burned an effigy of President Barack Obama as well as the cross. Speaking of the alleged killing spree, Obama said Tuesday, "The United States takes this as seriously as if it were our own citizens and our own children who were murdered." The killing of innocent civilians is outrageous and it's unacceptable. It's not who we are as a country and it does not represent our military," he said. ABC News' Lee Ferran contributed to this report.