It is one of the most bizarre things we’ve ever seen. One minute the President of America goes on national television to announce that he has ordered our military to “degrade and ultimately destroy” the Islamic State of Iraq and the Levant. The next moment his state secretary goes on Cable News Network to make a declaration that CNN reported under the headline: “Kerry: U.S. not at war with ISIS.” It seems Mr. Kerry wants to draw a distinction between, on the one hand, a counter-terrorism operation, which is how he describes that in which are involved, and, on the other hand, war.

We doubt that Mr. Kerry did that expressly to cheer up the enemy, but such is no doubt its effect. It suggests, after all, that Congress mightn’t be fully behind this expedition and that there are various limits to what we might be prepared to do in the course of the fight. This view is shared by James Taranto of the Wall Street Journal, who issued a typically wonderful column on the point this afternoon (he used the word “tergiversatory” to describe the administration’s rhetoric). He noted that the president himself vowed that he would not “get dragged into another ground war in Iraq.”

The Sun favors action by Congress to correct this through a formal declaration that a state of war exists between America and ISIS. This kind of declaration has been made but five times in American history, in each case presaging victory. It is illuminating to look at the language the Congress used. Save for the declaration against Mexico, Congress has been short and to the point, usually using but a few sentences. They were recognitions of hostilities that already existed, meaning — and here the ISIS war would fit right in — that we didn’t start the wars that Congress declared.

The first declaration was made against Great Britain to recognize what became known as the War of 1812. “Be it enacted,” Congress said, that “war be and is hereby declared to exist.” To carry the same into effect Congress also authorized the president “to use the whole land and naval force of the United States” and to issue to private armed vessels “letters of marque.” Letters of marque are one of the basic war powers that the Constitution grants to Congress. They are licenses to private parties to conduct. We used them against the Barbary Pirates.

Most of the European countries have, by treaty, forsaken letters of marque. America refused to ratify. Within days of 9/11, Congressman Ron Paul tried to get Congress to grant letters of marque against Osama Bin Laden. Congress demurred. But it would make sense for Congress to throw Letters of Marque into the arsenal that Mr. Obama is authorized, at his discretion, to use. It sends a signal that nothing is off the table. Or, as Congress put it when in 1917 it declared war on Germany, the president was authorized “to employ the entire naval and military forces and the resources of the government.”

That’s the kind of signal a war declaration sends. It doesn’t mean that the president is shorn of discretion. It doesn’t necessarily mean we’re going to get into a land war in the Middle East. It just means that the enemy — and states with an interest — can be of no doubt that we are committed. In that sense a war declaration has the potential to make a wider war less likely than the kind of a-constitutional statement the President made in announcing his plan to degrade and ultimately destroy ISIS. That’s because the enemy has less hopes for getting relief from a peace movement.

And one more point. It was less than two years ago that the New York Times launched its editorial campaign to get Congress to repeal the authorization to use military force that the president had been granted to fight terror. Congress didn’t listen. Now the Times wants the president to go back to Congress to get an authorization that Congress declined to repeal. A war declaration would discard all this shilly-shallying. When the Founders were writing the Constitution at Philadelphia, a proposal was made to grant Congress the power not only to declare war but also to make peace. The Founders decided not to give Congress such an out. Our own interpretation is that once war is declared, the only party that can make peace is the enemy.