The United States “will destroy” the Islamic State “and any other terrorist organization that tries to harm us,” President Barack Obama said in a televised speech to the nation on Sunday night.

Speaking from the Oval Office, the president said the country faces new challenges in its 14-year war on terrorism but remains equipped to overcome the threat the ideology poses to America.

The speech came days after the husband-and-wife team of Syed Rizwan Farook and Tashfeen Malik killed 14 people and wounded 21 others in a mass shooting at San Bernardino, California. The brazen attack occurred during a holiday party for Farook’s coworkers on Wednesday.

“This was an act of terrorism designed to kill innocent people,” Obama declared in the speech.

Obama went on to say that other shootings at military installations in Fort Hood, Texas, and Chattanooga, Tennessee, were also acts of terrorism. The president said the nature of these attacks represent a fundamental shift in the face of terrorism, and the challenge it presents.

He said the country has been at war with terrorists since 9/11, when terrorists hijacked four airplanes in an elaborate plot that ultimately killed nearly 3,000 people. America has beefed up its security and intelligence operations and disrupted a host of terrorist plots in the years since.

“Over the last few years, however, the terrorist threat has evolved into a new phase,” Obama said. “As we’ve become better at preventing complex, multi-faceted attacks like 9/11, terrorists turn to less-complicated acts of violence like the mass shootings that are all too common in our society.”

While noting there was no evidence that Farook and Malik were directed by a terrorist group or that they were part of a broader conspiracy in planning and executing Wednesday’s shootings, Obama said “it is clear that the two of them had gone down the dark path of radicalization, a perverted interpretation of Islam that calls for war against America and the West.”

The FBI echoed that statement on Monday, with an official saying at a news conference that the bureau had evidence that Farook and Malik had been radicalized “for quite some time.” The probe into the shootings and the circumstances around them continued Monday afternoon.

In his Sunday night speech, Obama reaffirmed the country’s commitment to fighting terrorism.

He said “our military will continue to hunt down terrorist plotters in any country where it is necessary,” and noted that 65 countries have joined an American-led coalition that is carrying out airstrikes against ISIS interests. The United States is also providing training to forces in Iraq and Syria that are fighting ISIS militants on the ground, and deploying special ops in both countries. Coalition forces are working to disrupt ISIS in other ways, like cutting off its money supply (largely obtained through oil smuggling) and preventing it from adding manpower.

Obama noted global efforts to combat ISIS have increased since Nov. 13, when gunmen and suicide bombers linked to the group killed 130 people in multiple terrorist attacks in Paris. In particular, he said the exchange of intelligence between allies has surged since those attacks.

The president said technology has made it easier for groups like the Islamic State to corrupt the minds of people around the world. The terrorists are frequently able to use social media and the Internet to share their radical messages. Obama called for technology companies and law enforcement officials to make it more difficult for terrorists to hide behind computer screens.

He also called for the departments of State and Homeland Security to review the ‘fiancee visa’ waiver program that Malik, a Pakistani native who was living in Saudi Arabia, used to enter the United States. It’s been widely reported that she met Farook, a U.S. citizen, on an online dating site.

Obama also called for stricter gun laws, like making it more difficult to purchase assault weapons like the ones used in San Bernardino. He noted authorities simply can’t identify every potential mass shooter, but “what we can do — and must do — is make it harder for them to kill.”

While Obama outlined the steps America is taking against ISIS and to prevent future terrorist attacks at home, he also laid out a list of things that America should not do. Those included entering a ground war in the Middle East, which could be lengthy and ultimately play into the Islamic State’s hand. He also said the country shouldn’t fear or discriminate against Muslims, noting that the Islamic State “doesn’t speak for Islam” and was “part of a cult of death.”

“The threat from terrorism is real, but we will overcome it,” Obama said in his televised comments. “We will destroy (ISIS) and any other organization that tries to harm us.”