President Barack Obama will make a rare primetime address Sunday laying out 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 hoped to reassure the US public, spooked by a seemingly new type of terror attack on the home front.
IS has praised the San Bernardino shooters, Syed Farook and his Pakistani wife Tashfeen Malik, as "soldiers" of its self-proclaimed caliphate, while stopping short of claiming outright credit for the attack.
Obama declared Saturday that the United States "will not be terrorized."
"I think what you'll hear the president say is to call on the American people to not give into fear," Lynch told NBC television. "You may hear him call on Congress to review measures and take action as well."
The Oval Office address is set for 8 pm Sunday (0100 GMT Monday), and will tackle "the broader threat of terrorism, including the nature of the threat, how it has evolved, and how we will defeat it," according to the White House.
The FBI is probing Wednesday's shooting at an office party in San Bernardino as an "act of terrorism." If confirmed to be terror-related, it would be the deadliest such assault on American soil since the September 11, 2001 attacks.