The United States will conduct air strikes on Islamic State strongholds in Syria, President Barack Obama announced Wednesday, saying the militant group, also known as ISIS or ISIL, poses a threat to people in the region, including U.S. citizens. "My highest priority is the security of the American people," Obama said. So the U.S. will lead a “broad coalition” to "degrade and ultimately destroy the terrorist group." 

"I will not hesitate to take action against ISIL in Syria, as well as Iraq," Obama said. "This is a core principle of my presidency: if you threaten America, you will find no safe haven. "

"It will take time to eradicate a cancer like ISIL," Obama said. But he laid out the strategy that he and an international coalition will employ.

The president called on Congress to approve additional funding to arm and train moderate rebels on the ground in Syria. (The president plans to brief Congressional leaders Thursday morning.) He also emphasized that Syrian President Bashar Assad is not an ally in the fight against the militant group, and made it clear that U.S. attacks on ISIS are not intended to -- even inadvertently -- strengthen Assad's grip on power.

"In the fight against ISIL, we cannot rely on an Assad regime that terrorizes its people; a regime that will never regain the legitimacy it has lost," he said, adding: "We must strengthen the opposition as the best counterweight to extremists like ISIL, while pursuing the political solution necessary to solve Syria’s crisis once and for all."

(One issue: The U.S. has very few trustworthy allies on the ground in Syria. Although Obama said the U.S. would back moderate rebels, the loyalties of smaller extremist groups on the ground fluctuate and some have even pledged allegiance to ISIS.)

Obama's four-point strategy to combat ISIS highlighted the importance of expanding the U.S. current air campaign in Iraq. America will send an additional 475 U.S. troops to support Iraqi and Kurdish troops with "training, intelligence and equipment." The U.S. will ramp up military assistance to the opposition, Obama said; will "draw on our substantial counterrorism capabilities" along with our partners; and will continue to provide humanitarian aid to innocent civilians.

In two weeks, the president said, he will chair a UN Security Council meeting "to further mobilize the international community." 

He took care to emphasize that the attack on ISIS would be the work of a "broad coalition. "Already, allies are flying planes with us over Iraq," he said, and Secretary of State John Kerry will be traveling across the Mideast and Europe "to enlist more partners in this fight -- especially Arab nations." America's partners include a 10-member NATO coalition, which includes a very reluctant Turkey. Obama said earlier this week that they would be the “core” group involved in his anti-ISIS strategy along with a strong Sunni driving force and an “inclusive” Iraqi government.

Obama also underlined that this was not a return to earlier wars. "I want the American people to understand how this effort will be different from the wars in Iraq and Afghanistan," he reiterated. "It will not involve American combat troops fighting on foreign soil." 

Syria is the militants’ main operational hub, making it an essential target in any plan to “dismantle” the group. This will be the first time the U.S. has conducted airstrikes against Syria. Just a year ago, in the wake of Assad's chemical attacks on his own people, Obama drew a "red line" that he said would provoke a strong American response if crossed. But the rise of ISIS has brought down the bombs and drones that Assad's own brutality did not. 

ISIS spent the summer seizing land about the size of Belgium in Iraq and Syria and then declared its stolen territory a caliphate. They succeeded in blurring the border between Syria and Iraq and are threatening to do the same across the region. International leaders deemed the militants a global threat after they beheaded two U.S. journalists on video and warned it would do the same to other Westerners currently in ISIS's posession. 

On Tuesday, the president said Congress' approval was not necessary for him to approve airstrikes. Republicans are scheduled to meet Thursday morning to discuss the matter, and if approved, planes could be over Syria as early as Thursday night.

Given U.S. officials’ rhetoric on the Islamic State in the last few weeks, it’s likely that Congress will approve the strike. The American public also appears to support military action, with fears of terrorism at a post-9/11 high. Six in 10 Americans support a strike against ISIS, according to a new NBC News/WSJ poll

For some legislators, simply allowing Obama to have his way is a safe bet, politically. “A lot of people would like to stay on the sideline and say, ‘Just bomb the place and tell us about it later,’” Representative Jack Kingston, Republican of Georgia, who supports having an authorization vote, told the New York Times. “It’s an election year. A lot of Democrats don’t know how it would play in their party, and Republicans don’t want to change anything. We like the path we’re on now. We can denounce it if it goes bad, and praise it if it goes well and ask what took him so long.”

This is Obama's second move in the battle against ISIS. Last month, the president authorized air strikes on ISIS strongholds in Iraq (without consulting Congress) in order to protect U.S. interests and to help a humanitarian crisis facing the Kurdish population in Iraq. When ISIS entered Iraq, it threatened to eradicate an entire minority population, the Yazidi sect. Militants were also able to seize many of the countries resources including oil fields, marijuana plantations and for a time, the Mosul Dam, which would have given them the ability to flood Baghdad.

The president said the roughly 150 air strikes in Iraq had been very successful thus far. Alongside air strikes, the U.S. and Iran armed Iraqi and Kurdish troops who were able to keep ISIS militants at bay and regain control of some of Iraq’s resources.

"These strikes have protected American personnel and facilities, killed ISIL fighters, destroyed weapons, and given space for Iraqi and Kurdish forces to reclaim key territory," Obama said. "These strikes have helped save the lives of thousands of innocent men, women and children."

"American power can make a decisive difference, but we cannot do for Iraqis what they must do for themselves, nor can we take the place of Arab partners in securing their region," Obama said. "That’s why I’ve insisted that additional U.S. action depended upon Iraqis forming an inclusive government, which they have now done in recent days."

ISIS was founded in 2004, born from the remains of a U.S.-led invasion to oust former Iraqi President Saddam Hussein. Having little success in Iraq, the militants moved to Syria, which had become a breeding ground for a mixed bag of extremist groups during the civil war. The Syrian civil war gave ISIS militants free reign to take over towns, to boost their bank accounts and build themselves up in safety, knowing that very few international powers wanted to intervene with Syrian president Assad in power.

While Syria is its central operational hub, ISIS wants to create Sunni state that spans the region with the Caliph Abu Bakr al-Baghdadi as its leader. In addition to the multiple extremist groups who have already pledged allegiance to the Islamic State, it has also been able to recruit foreign fighters, many of whom are from Western countries. This presents a different but no less dangerous ISIS threat to the global communityWestern fighters hold passports to their home countries and some fear they may come back to create sleeper cells or even carry out attacks in the name of the Islamic State.

"Our intelligence community believes that thousands of foreigners -- including Europeans and some Americans -- have joined them in Syria and Iraq," Obama said. "Trained and battle-hardened, these fighters could try to return to their home countries and carry out deadly attacks."

But ISIS does not merely aim to killing “infidels.” ("ISIL is not 'Islamic,'" Obama pointed out; "the vast majority of ISIL's victims have been Muslim.") The group has used its acts of terror  in a way unlike anything experts have seen before. It has a sophisticated media center that publishes news from the Islamic State, often highlighting how happy everyone is. It films a YouTube video series, has cultivated an impressive Twitter presence and even publishes a monthly magazine, not unlike al Qaeda's Inspire magazine. But even al Qaeda has rejected ISIS as too violent.

"We cannot erase every trace of evil from the world, and small groups of killers have the capacity to do great harm," Obama said. "That was the case before 9/11, and that remains true today. That’s why we must remain vigilant as threats emerge."

"This is American leadership at its best: We stand with people who fight for their own freedom; and we rally other national on behalf of our common security and common humanity."