President Obama to address the nation tonight at 8 pm ET...why not wait till Mon for a news conference?

via White House.

On Sunday, December 6, at 8:00 pm ET, President Obama will address the nation from the Oval Office about the steps our government is taking to fulfill his highest priority: Keeping the American people safe.
He will provide an update on the ongoing investigation into the tragic attack in San Bernardino. He will also discuss the broader threat of terrorism -- including the nature of the threat, how it has evolved, and how we will defeat it.

He will reiterate his firm conviction that ISIL will be destroyed and that the United States must draw upon our values -- our unwavering commitment to justice, equality, and freedom -- to prevail over terrorist groups that use violence to advance a destructive ideology.

This is short fused.  Why rush a "talk to the nation" on Sunday night, instead of waiting till Monday? Do they have intel that another attack is imminent?