Obama needed to address some key questions, regarding his plan for Syria, how American troops would be used, whether he would seek approval from Congress and what other countries would help in this effort. Perhaps the most important question was: How serious of a threat is ISIS?
Here's a look at whether the president answered those key questions, and what else he said in his address.
The plan to go after ISIS in Syria
One of the biggest questions Wednesday night was whether Obama would order airstrikes in Syria. He answered that he "will not hesitate" to do so, because he intends to hunt down terrorists who threaten the U.S. "wherever they are." Obama did not say when bombs could start dropping on Syria, a country still mired in a civil war — one that Obama has resisted getting involved in since its start.
On increasing military support to Syrian opposition fighters, Obama hesitated to do that early in the war. Obama has now called on Congress to approve a $500-million funding request made earlier in the year to help train and arm those who have been fighting against Bashar al-Assad's government. They must be strengthened so they can now fight against ISIS, the president said.
Boots on the ground
Obama, who was determined to wind down the U.S. war in Iraq, has announced he is sending even more troops to the country. Hundreds were deployed in Iraq this summer to protect American personnel at the embassy and elsewhere, and assess Iraq's military capabilities and gather intelligence. Now, another 475 troops will be deployed, but they will not have a combat mission, the president said. The new troops will bolster the training, intelligence and equipment of the Iraqi and Kurdish forces.
"We will not get dragged into another ground war in Iraq," he vowed. Obama went out of his way in his Wednesday speech to tell war-weary Americans how this fight against ISIS is different from the wars in Iraq and Afghanistan. The approach here is to use U.S. power in the air, and provide support to boots on the ground that come from regional forces. This is a "counter-terrorism campaign," he carefully said.
America won't go it alone
"America will be joined by a broad coalition of partners," Obama explained, but he didn't name them. NATO countries, including Canada, have expressed their support and Obama said allies are already helping by flying planes over Iraq, sending arms, sharing intelligence and funding humanitarian aid. Obama told Americans that the effort to enlist more partners, particularly Arab nations, is ongoing.
Whether Obama should be seeking some kind of authorization from Congress to drop bombs on Syria and for his ISIS strategy in general is a subject of debate in Washington. The president had to acknowledge this in his speech Wednesday, and he did, saying he has the authority he needs to deal with ISIS, but he'd like to see a show of unity with Congress.
"So I welcome congressional support for this effort in order to show the world that Americans are united in confronting this danger," he said. Beyond their symbolic support, however, Obama also needs them to sign off on the funding request to arm and train the Syrian rebels.
The threat of ISIS to the U.S.
It's unusual for the president to make a prime-time speech to the nation. The fact that Obama did it Wednesday night means he wanted Americans to pay attention. He needed to tell them why he is sending their troops into harm's way once again and spending millions of dollars on a region that the U.S. has already poured millions into and where thousands of lives were lost.
Obama addressed the threat posed by ISIS by describing their brutality, mentioning their murders of American journalists James Foley and Steven Sotloff, and saying that Americas in the Middle East are at risk as are the people of Iraq, Syria, and the whole region.
"If left unchecked, these terrorists could pose a growing threat beyond that region, including to the United States," Obama said.
The group has threatened the U.S., although there is no specific plot to carry out an attack that intelligence agencies know of, Obama said. But Americans have gone to Iraq and Syria to fight with ISIS and these people could come home, "trained and battle-hardened" to carry out attacks.
Obama began his speech by laying out the ISIS threat and finished it off with a patriotic-sounding argument for American leadership, saying it's the "one constant in an uncertain world." If any Americans were questioning why the U.S. has to yet again get involved somewhere far from its own borders, this part of Obama's speech was his answer. The U.S. has the capacity and the will to fight terrorists, contain and cure Ebola, fend off Russian president Vladimir Putin, and the list went on.
The U.S. has to fight ISIS because the country's safety depends on it, and, it's the right thing to do, Obama told his fellow Americans.