Feds issue security warning after Afghan killings (CBS News) WASHINGTON - The FBI and Department of Homeland Security have issued an "awareness bulletin" to state and local law enforcement agencies telling them it's possible the killings of Afghan civilians, allegedly by a U.S. soldier, could spark retaliatory acts of violence in the United States. The bulletin, which went out late Wednesday, stresses there is no credible or specific threat information related to homegrown violent extremist responses. And the bulletin adds that it's "unlikely" the recent events in Afghanistan will move homegrown extremists to act. Afghans fume over transfer of accused U.S. gunman Afghan suspect in apparent runway attack dies Calculating the price of a civilian life in Afghanistan Nevertheless, a U.S. official said the bulletin was issued out of an abundance of caution with the goal of increasing awareness. "We encourage law enforcement and security officials, as well as the general public, to be vigilant for signs of mobilization to violence, particularly against U.S. military targets in the homeland," the official said. Officials said similar events in the past have not triggered retaliation attacks inside the United States. The real concern is the recent incidents in Afghanistan, and the publicity surrounding them, contributing to "radicalization," which eventually could lead to future plots and potential strikes.