Speaking from the Oval Office for just the third time in his presidency on Sunday evening, President Barack Obama said the war on terror has entered a “new phase,” but promised that the West “will overcome” the threat from groups like the Islamic State.

“The threat from terrorism is real,” he said, but “tough talk” alone won’t work. Instead, we “will prevail by being strong and smart.”

Obama: ISIS a ‘Cancer’ with No Immediate Cure

There is “no evidence” that the suspects in last week’s mass shooting in San Bernardino — 28-year-old Syed Rizwan Farook and his 27-year-old wife Tashfeen Malik — were directed by a foreign terrorist organization or were part of a broader plot against the U.S., Obama said. “But it is clear that the two of them had gone down the dark path of radicalization,” he said, “embracing a perverted interpretation of Islam that calls for war against America and the West. They had stockpiled assault weapons, ammunition, and pipe bombs. So this was an act of terrorism, designed to kill innocent people.”

In recent years, groups like the Islamic State have become skilled at using the Internet to influence people around the globe who are vulnerable to their messages, and ISIS leaders are encouraging followers to turn to tactics like mass shootings.

Republican presidential hopefuls and GOP congressional leaders regularly accuse the president of underestimating the threat, and of under-reacting to it. On Sunday evening, the president said otherwise:

“For seven years, I’ve confronted this evolving threat each morning in my intelligence briefing,” he said. “And since the day I took this office, I’ve authorized U.S. forces to take out terrorists abroad precisely because I know how real the danger is. As Commander-in-Chief, I have no greater responsibility than the security of the American people. As a father to two young daughters who are the most precious part of my life, I know that we see ourselves with friends and coworkers at a holiday party like the one in San Bernardino. I know we see our kids in the faces of the young people killed in Paris. And I know that after so much war, many Americans are asking whether we are confronted by a cancer that has no immediate cure.”

He used the rare prime time address to explain and argue for his approach of relying mostly on U.S. and coalition airstrikes while also assisting local forces and targeting the group’s finances. “Our military will continue to hunt down terrorist plotters in any country where it is necessary,” he said.

The threat continues to evolve, he said: “Our nation has been at war with terrorists since al Qaeda killed nearly 3,000 Americans on 9/11. In the process, we’ve hardened our defenses — from airports to financial centers, to other critical infrastructure. Intelligence and law enforcement agencies have disrupted countless plots here and overseas, and worked around the clock to keep us safe…Over the last few years, however, the terrorist threat has evolved into a new phase. As we’ve become better at preventing complex, multifaceted attacks like 9/11, terrorists turned to less complicated acts of violence like the mass shootings that are all too common in our society.”

San Bernardino isn’t the first such attack in our country, he made clear: “It is this type of attack that we saw at Fort Hood in 2009; in Chattanooga earlier this year; and now in San Bernardino. And as groups like ISIL grew stronger amidst the chaos of war in Iraq and then Syria, and as the Internet erases the distance between countries, we see growing efforts by terrorists to poison the minds of people like the Boston Marathon bombers and the San Bernardino killers.”

Since the San Bernardino shooting, the White House has renewed its calls to tighten the nation’s gun laws to potentially make it more difficult for ISIS-inspired individuals to legally purchase firearms. White House officials also have floated the idea of banning military-style assault weapons, something Republicans say would violate the Second Amendment.

Obama used his address to reiterate those calls. “What could possibly be the argument for allowing a terrorist suspect to buy a semi-automatic weapon?” he asked on Sunday.

He also on Congress to vote on a measure that would specifically declare war on ISIS, officially giving the ongoing conflict formal legal cover. But a “long and costly ground war in Iraq or Syria,” the president said, is precisely “what groups like ISIL want. They know they can’t defeat us on the battlefield…But they also know that if we occupy foreign lands, they can maintain insurgencies for years, killing thousands of our troops, draining our resources, and using our presence to draw new recruits.”

Another road we should not take, he said, is that of turning “against one another by letting this fight be defined as a war between America and Islam. That, too, is what groups like ISIL want.” He also said Muslims themselves have to stand against those groups: Refusing to give in to bigotry, he said, “does not mean denying the fact that an extremist ideology has spread within some Muslim communities This is a real problem that Muslims must confront, without excuse.”

Hours before Obama’s address, Senate Majority Leader Mitch McConnell said he hoped to hear Obama state that “he is willing to adapt to the threat and how he can better prepare our nation for a fight that will inevitably be passed on to his successor.”

McConnell wanted the president to describe the kinds of legal authorities he needs to step up U.S. efforts against ISIS, as well as the kinds of changes to the country’s military — and how much in additional funding to pay for them — would be necessary. The Kentucky Republican also called on Obama to propose re-establishing America’s “capture, interrogation, and surveillance capabilities.”

Notably, McConnell did not call on the president to tell the nation he is sending in conventional U.S. ground troops to fight ISIS in Iraq and Syria. Instead, he called for Obama to describe how the American-led coalition or NATO would cobble together a ground force capable to driving the group from Raqqa, a Syrian city that is its de facto base of operations.

Republican presidential candidates often speak of bombing ISIS out of existence, but have been short on specifics, with frontrunner Donald Trump saying he would go after the families of terrorists and terrorism suspects. Sen. Ted Cruz, R-Texas, on Saturday released a new television ad in which he vowed to “rebuild our military” and “kill the terrorists.”