The president discussed the U.S. mission against the militant group during his visit to Estonia on Wednesday.
The White House may not yet have a clear-cut strategy for weeding out Islamic extremists in Syria, but it does know the process is not going to be quick.
"Because of what's happened in the vacuum of Syria, as well as the battle-hardened elements of ISIS that grew out of al-Qaida in Iraq during the course of the Iraq War, it's going to take time for us to be able to roll them back," President Obama said of the Islamic State in Iraq and Syria during a press conference in Estonia on Wednesday morning.
He continued: "And it is going to take time for us to be able to form the regional coalition that's going to be required so that we can reach out to Sunni tribes in some of the areas that ISIS has occupied, and make sure that we have allies on the ground in combination with the airstrikes that we've already conducted."
ISIS released video footage Tuesday of the execution of Steven Sotloff, the second American journalist to be killed by the fighters this summer. The White House confirmed its authenticity early Wednesday.
"Steve's life stood in sharp contrast to those who have murdered him so brutally," Obama said. "They make the absurd claim that they kill in the name of religion, but it was Steven, his friends say, who deeply loved the Islamic world. His killers try to claim that they defend the oppressed, but it was Steven who traveled across the Middle East, risking his life to tell the story of Muslim men and women demanding justice and dignity."
When asked whether the U.S. objective is to contain or destroy ISIS, Obama said that "our objective is to make sure that ISIL is not an ongoing threat to the region," using a different name for the militant group.
"It's not only that we're going to be bringing to justice those who perpetrated this terrible crime against these two fine young men," the president said. "More broadly, the United States will continue to lead a regional and international effort against the kind of barbaric and ultimately empty vision that ISIL represents. And that's going to take some time, but we're going to get it done. I'm very confident of it."
Obama also suggested that his administration would have to make "the case to Congress" before taking any military action inside Syria because it "might require congressional approval."
In Iraq, the U.S. mission is clearer. Obama said that airstrike and humanitarian missions conducted in that country since June have "borne fruit." "What we've what we've seen is the strategy that we've laid out moving effectively."
In any case, the U.S. will remain in the Middle East for the foreseeable future. The White House announced Tuesday night that the president had authorized sending 350 noncombat troops to Baghdad to protect Americans in the area.
"What I've said from the start is, is that this is not going to be a one-week or one-month or six-month proposition," Obama said Wednesday.