Washington:
President Barack Obama will make a rare primetime address Sunday laying out how he plans to keep Americans safe and defeat the Islamic State group, days after 14 people were shot dead in California.
Obama's top law enforcement officer, US Attorney General Loretta Lynch, said the president planned to give reassurance to a US public that has become jittery about more possible terror attacks on the home front.
"The president understands the country is very concerned about this issue, and I think what you'll hear from him is a discussion about what the government is doing to ensure our highest priority," Lynch told NBC television's "Meet the Press" program.
"You may hear him call on Congress to review measures and take action as well," Lynch said on Sunday.
"But I think what you'll hear the president say is to call on the American people to not give into fear."
The Oval Office address is scheduled for 8 pm Sunday (0100 GMT Monday).
Obama declared Saturday that the United States "will not be terrorized," as IS praised the married couple behind the mass shooting in San Bernardino as "soldiers" of its self-proclaimed caliphate.
- An exhortation to 'uphold our values' -"We are Americans. We will uphold our values -- a free and open society," the president said in his weekly address.
Investigators are combing over evidence and looking into the background of Syed Farook, 28, and his 29-year-old Pakistani wife Tashfeen Malik, who opened fire Wednesday at a social services center.
The FBI said federal agents raided a property in Riverside, California, but declined to provide details.
The FBI is investigating the shooting as a possible act of terrorism.
NBC News reported that the FBI had searched the home of Enrique Marquez, a friend of Farook's who originally bought the assault rifles used in the shooting but who is not considered a suspect.
If the shooting is proven to be terror-related, it would be the deadliest such assault on American soil since the September 11, 2001 attacks.
Obama last gave an Oval Office address in August 2010 to mark the end of US combat operations in Iraq.
In addition to an update on the probe, Obama will "discuss the broader threat of terrorism, including the nature of the threat, how it has evolved, and how we will defeat it," the White House said.
Top security officials have indicated that the two deceased suspects had been radicalized.
But the White House and the FBI say there are no signs they were part of a larger group or terrorist cell.
In an English radio broadcast, IS praised the two as "soldiers of the caliphate" and martyrs, but did not specifically say they were members of the group.
The heavily-armed pair, who also wounded 21 in their attack, died in a shootout with police after a manhunt.
The rampage was the worst in the United States in three years and revived impassioned debate on gun control in a country where such mass killings have become routine.
The New York Times on Saturday published a front-page editorial -- the first since 1920 -- calling for an end to "the gun epidemic in America."
In contrast, the president of Liberty University, a conservative Christian school, urged students to get permits to carry concealed weapons on campus.
"I've always thought if more good people had concealed carry permits, then we could end those Muslims before they walked in," Jerry Falwell Jr. said at the school's convocation to loud cheers.
- Quiet couple -Authorities say Malik and Farook, who was US-born, carefully planned their attack.
David Bowdich, the assistant FBI director in charge of the Los Angeles office, said investigators were examining a Facebook posting in which Malik is believed to have pledged allegiance to IS leader Abu Bakr al-Baghdadi, made around the time of the attack.
The family's attorneys said that while the two were devout Muslims, there was no hint they had become radicalized.
Relatives have been at a loss to explain what triggered the killing spree, describing them as a quiet couple who kept to themselves.
They had a six-month-old daughter, whom they left with Farook's mother before the shooting.
- 'New approach needed' -Officials in Washington has long warned of the threat of homegrown, self-radicalized extremists.
"We have moved to an entirely new phase in the global terrorist threat and in our homeland security efforts," Homeland Security Secretary Jeh Johnson told the Times.
Terrorists have "in effect outsourced attempts to attack our homeland. We've seen this not just here but in other places," he added.
"This requires a whole new approach, in my view."
Donald Trump, the 2016 Republican presidential frontrunner, gave little doubt as to how he would deal with any terror threat from within.
"I would handle it so tough, you don't want to hear," CNN quoted him as saying.