This article is from the archive of our partner National Journal

Never has a declaration of war been so cautious. Never has an American president spent so much time talking about what the declaration doesn't mean and left so many questions about what it does mean.

But what President Obama put forth in his nationally televised address Wednesday night still was a declaration of war—even if he did prefer to call it a "counterterrorism campaign." What made it more remarkable was that it was delivered by a president who ran for office on an antiwar platform and hoped his legacy would be leaving the nation at peace.

This is the president who, 19 months ago in a speech at the National Defense University, stated that the war on terrorism, "like all wars, must end"; who 33 weeks ago in his State of the Union address said, "America must move off a permanent war footing"; and who 14 days ago told reporters that "we don't have a strategy yet" for combating the Islamist terrorist group, ISIS, that has seized broad swaths of territory in Iraq and Syria.

But here he was Wednesday evening unveiling a strategy and vowing to "degrade and ultimately destroy" the Islamic State in Iraq and Syria and "hunt down terrorists who threaten our country wherever they are."

And he was doing it precisely one year to the night that he stood in the same place in the White House Cross Hall looking into the East Room. It was there, on Sept. 10, 2013, that he backed down from his threat to launch military strikes into Syria to punish dictator Bashar al-Assad. He used that speech to appeal to the emotions of war-weary Americans, drawing what he called a "sickening" picture of Assad's massacre of civilians, of "men, women, and children lying in rows, killed by poison gas." He didn't even mention that more than 160,000 civilians have perished in the fighting in Syria. But neither the president's talk of children dying nor the broader reports of civilian victims moved this country to support American intervention.

One year later, it has taken just two deaths to accomplish that. The sea change in public opinion in favor of intervention is explained by an NBC News/Wall Street Journal poll released Tuesday that found that 94 percent of Americans are aware of the news of the beheading of journalist James Foley, the first of the two American journalists brutally and publicly killed by ISIS. That makes the beheading the most-followed story by the American public in the last five years.

So the president began his speech not needing to persuade the nation that ISIS is a real threat. But he did have to persuade Americans that he has a strategy for countering that threat and that he will do what it takes to keep the homeland safe. His success at that task cannot be measured until the White House shows it can effectively follow up on the speech. Like any Obama address, it was well-delivered. But the president has shown he is better at eloquence than at persuasion. And when it comes to taking the country to war, much more than eloquence is demanded.

It is on that score that the president and the White House need to do well beyond what could be accomplished in a single speech. What he stressed was what this operation is not—it is not, he said, another ground war, it is not another Iraq or Afghanistan. And it is not, he emphasized over and over, a solo American operation. Fully eight times in the 14-minute speech he called attention to the "partners" who will be doing much of the heavy lifting in the battle.

Before the speech, the White House made a determined effort to defend the timing of his decision to launch airstrikes across the Syrian border and to provide support to the moderate anti-Assad rebels. Aides pointed out—fairly—that the president all along has said he would not act until he could persuade balky Iraqis to form a government that could appeal across sectarian lines. Obama believed that military operations would be fruitless without such a government in place. On Tuesday, the Iraqis yielded and Haidar al-Abadi took office as prime minister. White House aides also defended Obama's decision-making, saying he wanted to "take the time to get it right." Obama, said one senior official, "does not shoot first and ask questions later."

But now that the decision has been made and the speech delivered, many questions remain unanswered. How can the United States be sure that the anti-Assad rebels to be aided are not extremists? How can the air attacks inside Syria be guided without any American spotters on the ground? How can attacks in Syria be coordinated with Iran when the White House has promised there will be no discussion with the Iranian military? What will the operation cost? How will the "partner" countries share in that cost?

What is the exit strategy? How is victory defined? And, perhaps most important, how long will this war last? On this point, Obama sounded strikingly like his predecessor, President George W. Bush. "It will take time to eradicate a cancer" like ISIS, he said.

When military and administration officials head to Capitol Hill on Thursday, these are among the questions they will face. How they are answered will affect another unknown: How will Congress react to the president's insistence that he does not need further congressional authorization to launch this campaign? It is, Obama insists, covered by the Authorization for Use of Military Force resolution adopted after 9/11—even though he called for its repeal in his National Defense University speech. He said he would "welcome" further support from Congress, and the White House acknowledges he needs Congress to give him the authority to train the Syrian rebels. House Speaker John Boehner did not address that question after the speech. But, in a statement, he did note that "many questions remain about the way in which the president intends to act" and that "a speech is not a strategy."

Obama's speech Wednesday may have been a strong start. But it was just a beginning. Now come the tougher challenges of building the international coalition, answering those questions at home, and winning this fight abroad. However that's defined.

This article is from the archive of our partner National Journal.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.