A week ago, President Obama stood before the American people and promised that the expanding fight against the Islamic State — a vicious Sunni militant group known as ISIS or ISIL that is terrorizing parts of Iraq and Syria — would not mean a commitment of American ground troops. “As I have said before, these American forces will not have a combat mission,” he said.

On Tuesday, Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, had a very different message when he testified before the Senate Armed Services Committee. “If we reach the point where I believe our advisers should accompany Iraqi troops on attacks against specific ISIL targets, I’ll recommend that to the president,” he said, citing a potential attempt to retake the strategic important Iraqi city of Mosul as an example.

There is no way to read this other than as a reversal from the firm commitment Mr. Obama made not to immerse the country in another endless ground war in the Middle East.

Even though General Dempsey’s remarks were conditional, the Obama administration has turned on a dime in record time and opened the door to deeper, more costly American involvement even before the strategy is fully sketched out. And this is happening without Congress ever giving Mr. Obama the authority to wage war.