US President Barack Obama speaks on the phone with Saudi Arabia's King Abdullah from the Oval Office of the White House in Washington, Sept 10, 2014. President Barack Obama called Saudi Arabia's King Abdullah on Wednesday ahead of an evening speech in which the US leader plans to lay out his strategy for defeating the militant group Islamic State, the White House said. [Photo/Agencies]

WASHINGTON - US President Barack Obama will deliver a prime time address Wednesday night to tell the Americans that he will combat the Islamic State (IS) forces with airstrikes "wherever they exist," according to the excerpts of Obama's address released by the White House.

"This counter-terrorism campaign will be waged through a steady, relentless effort to take out ISIL wherever they exist using our air power and our support for partner forces on the ground," said the excerpts of Obama's address.

In the accordance with excerpts, the US military campaign will aim to degrade and ultimately destroy ISIL through a comprehensive and sustained counter-terrorism strategy, but it will not involve American combat troops fighting on foreign soil.