Washington (CNN) -- It's time to go after ISIS in Iraq and Syria, President Barack Obama said Wednesday night in a nationally televised address intended to sell stepped-up military efforts to a war-weary public.
Announcing a broad campaign against the Sunni jihadists who have rampaged from Syria across northern Iraq, Obama announced an escalated U.S. military role as part of a strategy that includes building an international coalition to support Iraqi ground forces and perhaps troops from other allies.
U.S. airstrikes have been hitting the jihadists in Iraq.Those strikes will be expanded to ISIS targets in Syria, Obama said.
"I have made it clear that we will hunt down terrorists who threaten our country, wherever they are," he said. "That means I will not hesitate to take action against ISIL in Syria, as well as Iraq. This is a core principle of my presidency: if you threaten America, you will find no safe haven."
The declaration answered calls from a growing number of U.S. politicians for such a step, with increasing public support.
"This was a very difficult speech for him to give," CNN chief political analyst Gloria Borger said of a president who campaigned on ending wars in Iraq and Afghanistan. "He's inserted us into the middle of a Syrian civil war."

More U.S. forces to Iraq

Obama also announced another 475 American military advisers would go to Iraq, pushing the total figure to about 1,700. At the same time, he made clear the strategy differed from all-out war again in Iraq less than three years after he withdrew combat forces from the country.
"It will not involve American combat troops fighting on foreign soil," Obama said.
His address from the White House also sought to convince allies and the nation of a firm U.S. commitment to lead an international coalition to fight the jihadists who rampaged across northern Iraq from Syria this year. They are known as ISIS, ISIL and Islamic State.
Noting the formation of a new Iraqi government, which his administration has demanded, Obama announced that"America will lead a broad coalition to roll back this terrorist threat."

Objective: "degrade and ultimately destroy" ISIS

"Our objective is clear: We will degrade, and ultimately destroy, ISIL through a comprehensive and sustained counterterrorism strategy," he said.
Senior administration officials who briefed reporters before the speech on condition of not being identified said airstrikes against ISIS targets in Syria would occur "at a time and place of our choosing."
"We're not going to telegraph our punches by being specific about the time and nature of the targets," one official said, adding that "we will do that as necessary as we develop targets."
Also Wednesday, Obama shifted $25 million in military aid to Iraqi forces, including Kurdish fighters in the north combating the ISIS extremists. The aid could include ammunition, small arms and vehicles, as well as military education and training, State Department spokeswoman Marie Harf said.
U.S. diplomatic efforts this week seek to solidify the coalition.Secretary of State John Kerry left Tuesday to push Sunni leaders in Jordan and Saudi Arabia to join the United States and its allies in combating ISIS, while Defense Secretary Chuck Hagel and Lisa Monaco, the homeland security adviser, also will be in the region.

Saudis part of coalition

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"The Saudis made very clear that they support this mission, they will join us in this mission," a senior administration official said. "We are joined by very important Arab partners as well."
Obama has been criticized by conservatives and some Democrats for what they call a timid response so far to the threat by ISIS fighters. The recent beheading of two American journalists held captive by ISIS raised public awareness of the extremists and the threat they pose.
"We can't erase every trace of evil from the world, and small groups of killers have the capacity to do great harm. That was the case before 9/11, and that remains true today," Obama said.
ISIS poses a threat to the Middle East, including the people of Iraq and Syria, he said, adding:"If left unchecked, these terrorists could pose a growing threat beyond that region, including the United States."