WHITE HOUSE - President Barack Obama has told the American public last week's shooting attack in California was an "act of terrorism designed to kill innocent people."

In a rare televised address from the Oval Office late Sunday, Obama discussed the attack and sought to reassure Americans on the U.S. strategy to combat terror.

The president said the two killers had gone down the "dark path of radicalization, embracing a perverted interpretation of Islam." But he said there is no evidence yet that they were directed by any terrorist organization overseas, or that they were part of any broader conspiracy in the United States.

U.S.-born Syed Rizwan Farook and his Pakistani wife Tashfeen Malik killed 14 people and wounded 21 at a gathering of local government workers last Wednesday in San Bernardino, about an hour's drive east of Los Angeles. They also planted a pipe bomb that failed to go off, then fled in a large black sport utility vehicle.

Watch Obama's remarks about US counterterrorism efforts:

?Their car was later spotted and they were killed as they exchanged gunfire with police.  Now, the Federal Bureau of Investigation is investigating what led Farook and Malik to carry out the attack.

Federal officials said that Malik pledged allegiance to an Islamic State leader in a Facebook posting and that Farook had contact with individuals linked to terror groups.

An undated combination of California Department of
An undated combination of California Department of Motor Vehicles photos shows Tashfeen Malik, left, and Syed Farook, the husband and wife who died in a gunbattle with authorities after a mass shooting in San Bernardino, Calif., Dec. 2, 2015.

?Terrorist threats

Obama said the U.S. has hardened its defenses against terrorist threats. He noted that intelligence and law enforcement agencies have disrupted countless plots, both at home and overseas and that the U.S. military and counterterrorism professionals have relentlessly pursued terrorist networks overseas, disrupting safe havens in several different countries.

But he said that over the last few years, terrorists have turned to "less complicated acts of violence," like the mass shootings that he said are "all too common in our society," including the San Barnardino attack.

Although the president said his administration is constantly examining its counter-terrorism strategy to see if additional steps are needed to protect Americans, his speech included no new policy changes or announcements.

Instead, he sought to reassure the American public that he and his administration are taking the threat of terrorism seriously.

Watch related video report from VOA's Michael Bowman:

Obama said he understands that Americans are asking if "we are confronted by a cancer that has no immediate cure." But, using an acronym for the Islamic State terror group, he pledged, "We will destroy ISIL and any other organization that tries to harm us."

He promised the U.S. military will continue to hunt down terrorist leaders in any country where it is necessary. He also said the U.S. will continue to provide training and equipment to tens of thousands of Iraqi and Syrian forces fighting IS on the ground. He said the U.S. is working with allies to cut off terrorist financing and prevent the terrorists from recruiting more fighters, and to counter the "vicious ideology" that IS promotes online. And he said the international community has begun to work toward establishing a timeline to bring an end to the Syrian war.

Yanira Perez (2-R) wipes her eyes as she and her m
Yanira Perez (2-R) wipes her eyes as she and her mother, Marcela, pay respects at a makeshift memorial to honor the victims of Wednesday's shooting rampage, Dec. 5, 2015, in San Bernardino, California.

Gun laws

The president said Congress should act to make sure no one on the U.S. no-fly list is able to buy a gun. He again reiterated his call for lawmakers to tighten U.S. gun laws, saying no matter how effective law enforcement and intelligence are, they cannot identify every would-be shooter. He called it a matter of national security to prevent potential killers from getting guns.

Earlier, Senate Majority Leader Mitch McConnell called on the president to outline plans for a ground force to dismantle the IS terror group.

But Obama told his audience the United States will not be pulled into a protracted ground war in Syria or Iraq, even as it steps up the fight against Islamic State.

"We should not be drawn once more into a long and costly ground war in Iraq and Syria. That's what groups like ISIL want," Obama said.

Finally, the president implored Americans not to turn against Muslims at home, saying Islamic State is driven by a desire to spark a war between the West and Islam. Still, he called on Muslims in the U.S. and around the world to take up the cause of fighting extremism.

Obama said he is confident that "we will succeed in this mission, because we are on the right side of history." He appealed to Americans, "Let's not forget that freedom is more powerful than fear."