U.S. President Barack Obama spoke by phone with Saudi King Abdullah on Wednesday and met his top national security and intelligence advisors ahead of his prime time speech on ISIL.

U.S. President Barack Obama spoke by phone with Saudi King Abdollah on Wednesday and met his top national security and intelligence advisors ahead of his prime time speech on ISIL.

Obama called Abdullah from the Oval Office, underlining Saudi Arabia's role as a potentially key member of the international coalition Obama is trying to build to allegedly take on the "jihadist" group.

The call preceded his speech to the nation at 9pm (0100 GMT Thursday) about his new "strategy" to take on ISIL and came ahead of a planned visit to Saudi Arabia by Secretary of State John Kerry.

Obama also gathered what is effectively his war cabinet in the secure Situation Room of the White House. The meeting included Vice President Joe Biden, Secretary of Defense Chuck Hagel, senior leaders of the military and the chiefs of U.S. intelligence agencies.