It's tough to argue with someone who writes an entire column without including a declarative sentence.  So I hesitate to accuse John Podhoretz of advocating (or even considering) genocide.  He constructed his column in such a way that he can scurry away from the inferences a logical person would draw from the string of questions he asks.  Among those questions are:

What if the tactical mistake we made in Iraq was that we didn't kill enough Sunnis in the early going to intimidate them and make them so afraid of us they would go along with anything? Wasn't the survival of Sunni men between the ages of 15 and 35 the reason there was an insurgency and the basic cause of the sectarian violence now?

Podhoretz has a point (or maybe not, depending on whether he acknowledges the implications of what he's "asking").  If you have sufficient manpower and firepower you can flood a city or a country with stormtroopers, give them orders to round up and slaughter all the fighting-age men they find, and thereby utterly crush "the enemy."  That tactic was used pretty effectively (though not completely decisively) by Saddam Hussein against the Kurds in the 1980s and against the Shiites in the aftermath of the first Gulf War.  Saddam's response to the attempt on his life in Dujail was pretty much in line with what Podhoretz contemplates (though Saddam went a couple years younger than Podhoretz might, and murdered 13-year-old boys).

But it's not as easy as you might think.  You end up killing a lot of women and children, too.  That's partly because they get in the way as you go after the men.  It's also because, once you initiate mass slaughter for the purpose of "intimidat[ing] them and mak[ing] them so afraid of us they would go along with anything," you realize that there's no point, really, in sparing people based on their age or their gender.  You also realize, after you've been murdering and oppressing people for a while, that murder and oppression aren't discreet events.  You can't use them once for demonstration purposes and then abandon them.  Once you have your boot on a man's neck you'd better keep it there.  Who knows what he might do to you if you let him up off the ground?

Of course, there are alternatives to that kind of prolonged campaign of murder and oppression.  You can inflict death and destruction from above, before sending in ground troops to sift through the wreckage and order around the terrified survivors.  After all, "could World War II have been won by Britain and the United States if the two countries did not have it in them to firebomb Dresden and nuke Hiroshima and Nagasaki?"

This is the point Podhoretz wants to make, but is shrewd enough not to state outright:  we could have justifiably incinerated the men, women and children of Ramadi and Fallujah and west Baghdad in the spring of 2003.  We could have justifiably segregated Sunni men from Shia men and slaughtered the former wholesale as the insurgency got underway in the fall of that year.  That would have been justified because it's necessary to defend our lives and our liberal democratic values.  We know this because we could never have defeated Nazi Germany or Imperial Japan without sustained counter-population bombing.

If you're confused by the sudden substitution of Nazi Germany for Iraq, don't be.  You can do anything at all to Nazi Germany; people might get upset if you did the same things to Iraq.  If you're killing hundreds of thousands of civilians in Nazi Germany everyone knows you have to do it (at least they do now—Christopher Hitchens notes that, contrary to Podhoretz's bellicose fantasies, many people weren't so cavalier about it back then).  But if you suggest in a newspaper column that it's a shame we're not killing hundreds of thousands of Iraqis then people might reasonably ask why so many innocent people should die.  They might wonder how that squares with choosing to launch a war to bring the benefits of freedom and democracy to the Iraqi people.  They might wonder if, for certain pundits, all that rhetoric was just a cover for bloody-mindedness and an excuse to chortle as the bombs fell.

Better to frame the whole thing as a series of questions, and make sure you mention the Nazis as often as possible.  That way you can make your point without having to take responsibility for your feeble-minded endorsement of criminality.