WHITE HOUSE - President Barack Obama proposed a substantially expanded American military campaign against Islamic State militants, vowing a “relentless effort” to wipe out the terrorists “wherever they exist,” he told the nation Wednesday night.

Obama laid out the new strategy in a televised White House speech as the U.S. and its allies face the growing threat of rising Islamist extremism in Iraq, Syria and other parts of the volatile Middle East and North Africa region.

Obama to Expand Offensive Against Islamic State Group

Obama's plan includes training and arming Iraqi security forces as well as vetted Syrian opposition fighters in order to help both groups battle fighters from the Islamic State, also known as ISIS or ISIL.

Obama to Expand Offensive Against Islamic State Group

But Obama emphasized that the fight against Islamic State militants will be different from recent U.S. wars in Iraq and Afghanistan.

Obama to Expand Offensive Against Islamic State Group

“It will not involve American combat troops fighting on foreign soil. 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.”

“This strategy of taking out terrorists who threaten us, while supporting partners on the front lines, is one that we have successfully pursued in Yemen and Somalia for years,” Obama said.

The president also discussed the possibility of expanding American airstrikes against militant strongholds across the Iraqi border into Syria and indicated that allies in Europe, the Middle East and elsewhere are ready to join the U.S.-led counter-terrorism campaign.

“With a new Iraqi government in place, and following consultations with allies abroad and Congress at home, I can announce that America will lead a broad coalition to roll back this terrorist threat,” Obama said.

“Our objective is clear: we will degrade, and ultimately destroy, ISIL through a comprehensive and sustained counter-terrorism strategy.”

As part of that effort, the U.S. also will send an additional 475 service members to Iraq in a non-combat role to support Iraqi and Kurdish forces, the president said.

The American-led coalition will mount a strategy to stem the flow of foreign fighters to the Islamic State, and ramp up humanitarian assistance to those displaced by militants.

Earlier Wednesday, the White House announced it would provide $25 million in immediate military assistance to the new Iraqi government as part of its efforts to combat the Sunni extremist group, which controls substantial swathes of territory in northern and western Iraq.

According to sources, Saudi Arabia has pledged its full commitment to that effort, and U.S. troops will train Syrian opposition fighters on Saudi soil.

The effort is dependent on the U.S. Congress approving $500 million to train and arm the rebels.

The Saudi decision emerged after Obama spoke by phone earlier in the day with Saudi King Abdullah, who has pushed the American government to do more resolve the Syrian conflict.

Secretary of State John Kerry, now visiting Baghdad, will meet with leaders across the region in the coming days.

Republican House Speaker John Boehner after the president's speech Wednesday saying Obama has finally begun making the case that "destroying this terrorist threat requires decisive action." But Boehner also said a "speech is not the same thing as a strategy," and that there are still questions about the president's intentions.

Republican Ed Royce, the chairman of the House Foreign Affairs Committee, said it remains to be seen whether the administration, "after much delay and denial, develops and executes the sustained commitment needed" to destroy the Islamic State.

Republican Representative Marsha Blackburn of Tennessee told VOA she would have preferred Obama be more definitive in identifying which nations would take part in the coalition.

Democratic Representative Eliot Engel of New York also spoke to VOA, saying that he strongly supports Obama's plan while adding that it is "only the opening salvo."

But Alaska Democratic Senator Mark Begich, a member of the Armed Services Committee, said he would not give the president "a blank check to begin another land war in Iraq." Begich -- one of many Democratic senators facing a tough re-election contest in November -- said Congress must approve any military campaign beyond the current airstrikes against IS.

Public opinion polls this week show a majority of Americans support action against the militants.

Meanwhile, Senate Democratic leaders prepared legislation that would authorize the U.S. military to arm and train pro-Western Syrian rebels in the fight against Islamic State militants, according to Senate Democratic aides.