President Obama on Saturday pledged to keep up U.S. efforts to combat the Islamic State in Iraq and Syria (ISIS) in the wake of the terror attacks in Brussels this week and mourned the Americans who were killed in the bombings.

“Yesterday, we learned that at least two Americans were killed,” Obama said in his weekly address. “We pray for their families and loved ones. At least 14 Americans were injured. And we pray for their full recovery, along with everyone else affected by these attacks.”

But the president expressed his confidence in the U.S. campaign against ISIS, which claimed responsibility for the Brussels attacks, and touted the military’s success in targeting key ISIS leaders. On Friday, the Pentagon announced it had killed the group’s second in command earlier in the week, the second high-profile leader to be taken out by the U.S. this month.

“We’ve been taking out ISIL leadership, and this week, we removed one of their top leaders from the battlefield — permanently,” Obama said, using an alternate acronym for the terror group. “A relentless air campaign and support for forces in Iraq and Syria who are fighting ISIL on the ground has allowed us to take approximately 40 percent of the populated territory that ISIL once held in Iraq. We’re supporting Iraqi Security Forces who are beginning to put pressure on the ISIL stronghold of Mosul. And we will not stop until ISIL’s safe havens are destroyed.”

The president also emphasized that law enforcement and intelligence agencies are working to disrupt terrorist activities outside of Syria and Iraq.

“ISIL poses a threat to the entire civilized world,” he said. “That’s why we’ve been leading a truly global coalition that will be vital to our success. Secretary Kerry is leading an international effort to bring the Syrian civil war to an end, a critical piece of restoring stability to that war-torn part of the world.”

Obama also used the weekly address to push back against Republican presidential contenders' responses to the terror attacks, most notably Donald TrumpDonald John TrumpRed states find there’s no free pass on Medicaid changes from Trump Trump meets with Moon in crucial moment for Korea summit The Memo: Trump flirts with constitutional crisis MORE’s call to shut down the southern border and Ted CruzRafael (Ted) Edward CruzSenators near deal on sexual harassment policy change Senate GOP urges Trump administration to work closely with Congress on NAFTA Five Republican run-offs to watch in Texas MORE’s proposal to increase law enforcement patrols in Muslim neighborhoods.

“As we move forward in this fight, we have to wield another weapon alongside our airstrikes, our military, our counterterrorism work, and our diplomacy,” the president said. “And that’s the power of our example. Our openness to refugees fleeing ISIL’s violence. Our determination to win the battle against ISIL’s hateful and violent propaganda — a distorted view of Islam that aims to radicalize young Muslims to their cause.”

“In that effort, our most important partners are American Muslims,” he added. “That’s why we have to reject any attempt to stigmatize Muslim-Americans and their enormous contributions to our country and our way of life. Such attempts are contrary to our character, to our values, and to our history as a nation built around the idea of religious freedom. It’s also counterproductive. It plays right into the hands of terrorists who want to turn us against one another, who need a reason to recruit more people to their hateful cause.”