On Monday, President Barack Obama spoke at the G-20 summit in Turkey, reaffirming the United States' commitment to defeating the ISIS, an extremist terrorist organization that has claimed responsibility for a series of attacks in Paris that killed more than 120 people last week.

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Obama outlined the U.S. strategy against ISIS and called on other countries to provide military and intelligence support to help curb terrorism in the Middle East and North Africa. He also explained why it was important to continue to accept refugees, including those fleeing terrorism in Syria.

Here are the important quotes from Obama's G-20 speech.

1. "A strategy has to be one that can be sustained."

While the U.S. military has the resources necessary to launch a campaign against ISIS on the ground, Obama said that he and his advisors remained opposed to a strategy that involved putting American soldiers in Syria. Instead, the country will continue to execute air strikes against the terrorist group, targeting their leadership and infrastructure.

2. "What I do not do is to take actions either because it is going to work politically or it's going to somehow in the abstract make America look tough or make me look tough."

Obama said that the country needed to act on intelligence and maintain a strategic approach in order to defeat ISIS. Acting on impulse or attacking the country for political reasons would be the wrong approach, he argued.

3. "Tragically, Paris is not alone. We've seen outrageous attacks by ISIL in Beirut, last month in Ankara, routinely in Iraq."

Obama expressed grief over the shootings and suicide bombings that killed more than 120 people in Paris last week, but he also recognized that violent extremism was an ongoing problem for other countries as well.

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In Beirut, Lebanon, two suicide bombings have killed at least 41 people this month, the deadliest violence that the country has seen since the end of the Lebanon civil war in 1990. More than 100 people died last month in Ankara, Turkey, where two bombs were detonated at a peace rally. The Islamic State claimed responsibility for all of these attacks.

4. "We don't kill people because they are different than us. That's what separates us from them."

Obama said that he admired the way that former President George W. Bush discussed religion in the wake of 9/11. He was "adamant and clear about the fact that this is not a war on Islam," and the president said that it was important to distinguish between Islam from the religious extremism that led to the attacks in Paris last week.

5. "Of course, the attacks in Paris remind us that it will not be enough to defeat ISIL in Syria and Iraq alone."

Obama described the unique challenges of waging a war against ISIS, which is a largely fragmented terrorist organization that exists in remote parts of the Middle East and Northern Africa. While the organization does have central bases in Raqqa, Syria, for example, the attacks in Paris highlight the difficulty of tracking individual ISIS members and anticipating their plans.

6. "Slamming the door in their face would be a betrayal of our values."

Following the attacks in Paris, some conservative politicians in France (as well as the U.S.) suggested that accepting refugees from the Syrian civil war puts countries at risk of violent extremism. Obama emphasized that we "have to remember that many of these refugees are the victims of terrorism themselves—that's what they're fleeing."

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7. "ISIL is the face of evil. Our goal, as I've said many times, is to degrade and ultimately destroy this barbaric terrorist organization."

By attacking oil refineries that ISIS has captured and uses to finance its terrorist activities, the U.S. hopes to degrade the group's influence in Syria. Obama also said that the military would continue to conduct targeted air strikes against the Islamic State in an effort to kill its leadership and military commanders.