(NBCNEWS) President Barack Obama vowed to "degrade and destroy" the Islamist militant group behind the beheading of a second American journalist . "We will not be intimidated," Obama told reporters during a visit to Estonia on Wednesday. "Those who make the mistake of harming Americans will learn that we will not forget and that our reach is long and that justice will be served."
Obama said that Americans were "repulsed" by the slaying of Steven Sotloff by Islamic State of Iraq and al-Sham (ISIS) militants, adding that such "horrific acts only unite us as country." He also vowed that the U.S. would continue to lead the battle against "the kind of barbaric and empty vision that [ISIS] represents." He said that mission would "take some time but it is going to get done," adding: "We will degrade and destroy [ISIS] so that it is no longer a threat to Iraq, the region and United States." A video showing Sotloff's beheading surfaced days after the journalist's mother pleaded with ISIS for mercy Its release followed the murder of James Foley who had also been held hostage by the Sunni extremists. The president said that Sotloff "deeply loved the Islamic world" and had risked his life traveling in the Middle East to "tell the story of Muslim men and women demanding dignity." He added: "Steven’s life stood in sharp contrast to those that murdered him so brutally."