President Barack Obama is to deliver a rare Oval Office address on the San Bernardino shootings.
The US leader will discuss the broader threat of terrorism, how it has evolved and how it will be defeated, the White House said.
The FBI is investigating the mass shooting by a married couple, that left 14 dead, as an act of terrorism.
Syed Rizwan Farook, 28, and his wife Tashfeen Malik, 29, were killed in a shootout with police.
The Islamic State militant group said in a radio broadcast that the couple that carried out the attack were IS supporters, but gave no indication that the group was involved in its planning.
The FBI is also looking into reports Malik posted a message on Facebook pledging allegiance to IS around the time of the attacks.
Mr Obama will provide an update on the investigations in the televised speech, due at 20:00 EST on Sunday (2pm, Monday NZ time).
It will be his third Oval Office address - they are reserved for events of national importance.
In his speech, Mr Obama will argue that the US must draw upon its values, namely its "unwavering commitment to justice, equality and freedom" to defeat terrorist groups.
In his weekly radio address on Saturday, President Obama said the US "will not be terrorised".