President Obama: 'We will destroy ISIL'

President Obama pledged to "destroy ISIL and any other organisation that tries to harm us" during a televised address from the Oval Office.

"The threat from terrorism is real but we will overcome it," the President added.

It comes after husband and wife Syed Rizwan Farook, 28, and Tashfeen Malik, 27, opened fire on co-workers at an office party on Wednesday in California.

Obama said there was no evidence that the pair were directed by terrorist groups overseas but said it was "an act of terrorism, designed to kill innocent people."

He urged the Americans of every faith to reject discrimination, saying that division plays into the hands of the terror group.

The President announced a series of measures to counter the threat from potential terrorists including better screenings for those who go to the country without a VISA and ensuring that no one on a no fly list is able to purchase a gun.

The President ruled out a "long and costly ground war" in Iraq or Syria but urged Congress to vote to authorise military force against the group.