President Obama has put America at the center of a widening war by expanding into Syria airstrikes against the Islamic State, the Sunni extremist group known as ISIS and ISIL. He has done this without allowing the public debate that needs to take place before this nation enters another costly and potentially lengthy conflict in the Middle East.

He says he has justification for taking military action against the Islamic State and Khorasan, another militant group. But his assertions have not been tested or examined by the people’s representatives in Congress. How are Americans to know whether they have the information to make any judgment on the wisdom of his actions?

There isn’t a full picture — because Mr. Obama has not provided one — of how this bombing campaign will degrade the extremist groups without unleashing unforeseen consequences in a violent and volatile region. In the absence of public understanding or discussion and a coherent plan, the strikes in Syria were a bad decision.

Mr. Obama has failed to ask for or receive congressional authorization for such military action. The White House claims that Mr. Obama has all the authority he needs under the 2001 law approving the use of force in Afghanistan and the 2002 law permitting the use of force in Iraq, but he does not. He has given Congress notification of the military action in Iraq and Syria under the 1973 War Powers Resolution, but that is not a substitute for congressional authorization.