It is time for President Obama to define for the nation the objectives of the air war the United States has launched against the Islamic State in Iraq. It is up to Congress to probe those objectives and the potential that the U.S. commitment may expand.

So far, the Obama administration gives the impression of making it up as it goes along.

"We don't have a strategy yet," the president said last week.

Meanwhile, Congress does not seem to have the stomach to push the issue. Democrats are hurting enough already as they head into the midterm election and fear further weakening the president and dragging down their prospects.

Republican hawks, who might criticize the president for not doing enough, risk alienating a public that has no interest in United States' involvement in another Mideast war. Better, it seems, to stick to the attack points on immigration, Obamacare and the deficit.

Historians can sort out who helped create the environment that bred the Islamic State. The Iraq War, unleashed at the behest of President George W. Bush, left Iraq weakened and its sectarian divisions exposed. The Islamic State exploited them.

President Obama could have pushed harder to keep a U.S. residual force, discouraging the weakening of the Iraq army due to sectarian-based favoritism. Meanwhile, his decision not to back any particular rebel group in the Syrian insurrection against President Assad made it easier for the Islamic State rebels to become the dominant insurgency, spilling into Iraq.

The question is what to do now. The Islamic State is a formidable force of an estimated 15,000 fighters, its ranks growing with recruits of angry young men attracted by its distorted brand of Islamic belief, terrorizing those who disagree and killing those who won't convert.

Unchecked, it could destabilize other Mideast nations. Meanwhile, its ability to recruit zealots from the West raises the potential some will return to launch attacks in Europe and the U.S.

Air power can harass this enemy and slow its advance, but it cannot defeat it. So what's the plan? Is it to weaken the Islamic State and leave the ground fights to Kurdish and Iraqi forces? What is the contingency if they can't succeed? Is the air campaign open-ended? What about pursuit of the Islamic State forces into Syria?

Many questions, not enough answers.