Before the United States plunges into a third war in the Middle East, let us think this one through, as we did not the last two.

What would be the purpose of establishing a no-fly zone over Libya? According to advocates, to keep Moammar Gadhafi from using his air force to attack civilians.

But if Gadhafi uses tanks to crush the rebellion, as Nikita Khrushchev did in Hungary and the Chinese did in Tiananmen Square, would that be OK?

What is the moral distinction between using planes to kill rebels and running over them with tanks? Do we Americans just want to see a fair fight?

To establish a secure no-fly zone, we would have to bomb radar installations, anti-aircraft batteries, missile sites and airfields, and destroy the Libyan air force on the ground, to keep the skies secure for U.S. pilots.

These would be acts of war against a nation that has not attacked us.

Where do we get the legal and moral right to do this? Has Congress, which alone has the power to declare war, authorized Barack Obama to attack Libya?

The president may respond to an attack on American territory or U.S. citizens, but Libya has not done that since Lockerbie, more than two decades ago.

Since that atrocity, George W. Bush and Condi Rice welcomed Gadhafi in from the cold, after he paid $10 million in blood money to the families of each of the Lockerbie victims.

What, then, is our present justification for attacking Libya?

The U.N. Security Council has not authorized military action against Libya. No NATO ally has been attacked. Why is Libya not a problem for the Arab League and the African Union, rather than the United States, 5,000 miles away?

Last week, the Senate whistled through a nonbinding resolution urging the creation of a no-fly zone. Call it the Sidra Gulf resolution.

But what are U.S. senators doing issuing blank checks for war eight years after George W. Bush cashed the last one to commit the historic blunder of invading Iraq? Do these people learn at all from history?

That war cost the Republican Party the Congress in 2006 and presidency in 2008. Far worse, it cost the country 40,000 dead and wounded, a trillion dollars, and the respect of hundreds of millions of Arabs and Muslims who saw the war as an imperial attempt to crush a nation that had done nothing to the United States.

Assume we attack Gadhafi’s air defenses, and in the collateral damage are a dozen children—like those kids collecting sticks on that hillside in Afghanistan—and Al-Jazeera spreads footage of their dismembered bodies across the Middle East, as commentators rail, “The Americans are killing Muslims again, this time for Libya’s oil.” The pro-democracy demonstrations across the Middle East would instantly become anti-American riots.

If we destroy Gadhafi’s air defenses, could we simply let the rebels and regime fight it out? If Libyans, seeing us intervene, rose up against Gadhafi, could we let them be massacred as Bush I let the tens of thousands of Shiites be massacred who rose up in 1991 against Saddam after Bush urged them to do so?