The "surge" is a success.

The "surge" is a failure.

Come September, it is likely that you'll be hearing both verdicts from politicians, analysts and your neighbors. And it's likely that evidence in Iraq will support either conclusion. That's because success and failure hinge on definitions and expectations - how much better or worse is Baghdad? - not to mention rough statistics and anecdotes that tell at best only a sliver of the story.

Those who see success will probably point to subsiding violence in some parts of Baghdad and the undeniably positive alliances with Sunni tribesmen in Anbar province against al-Qaida. Those who discern failure will find rising numbers of sectarian killings, suicide car bombings and an Iraqi parliament frustratingly unable or unwilling to set aside sectarian agendas to build a minimally functioning democracy.

There are few things more perilous than predicting events in Iraq. But absent a huge change in momentum, it seems likely that no matter what the statistics and arguments, September will bring political pressure for another shift in American strategy.

The "surge" has shown that more troops can bring a measure of security to some neighborhoods in Baghdad. But it also has shown the limits of such forces in the absence of effective Iraqi political leadership. And particularly in a war that has morphed into a complex mishmash of conflicts, involving militias, insurgencies, terrorists and criminals.

What can be said without hesitation is U.S. forces are stretched thin and the Iraqi army has yet to prove it is an effective fighting force. Some Iraqi units perform well. Others don't. The overall readiness of the force remains doubtful; the Pentagon's own analysis estimates as many as half the soldiers in Iraqi units fail to show for duty each day because of scheduled leaves, absences without leave or attrition. Some soldiers refuse to deploy when units are ordered outside their home territory.

U.S. Army Lt. Gen. Martin Dempsey recently said, "The clock in Baghdad turns at a different rate than the clock in Washington." In other words: Not as fast as Americans would like.

That's why, even as American troops are still surging into Baghdad, the administration is reported to be quietly contemplating a post-surge strategy. The Washington Post reported recently that the question for military officials is no longer whether the U.S. presence will be cut, but "how quickly, to what level and to what purpose."

Some military officials foresee a sharp drawdown of troops that is likely to begin by the middle of 2008, with roughly two-thirds of the current force out by late 2008 or early 2009, the paper reported.

What would a new American mission look like? One big clue: The Iraq Study Group report.

The president has hinted lately that he is warming to the panel's findings. So what we may see in the fall is the beginning of a long-term, sustainable U.S. presence, as the panel outlined. The report called for a gradual withdrawal of most U.S. combat troops. The U.S. mission would be refocused on training and supporting the Iraqi army and maintaining rapid-reaction teams to battle al-Qaida. It also would help Iraqis defend the border against incursions by its neighbors.

The panel's recommendation for a re-energized diplomatic effort with all the countries in the region - particularly Iran and Syria - is already haltingly taking shape. What needs to happen in Iraq now is largely beyond the scope of American military power. The administration's attempts to pressure Iraq's leaders to pass political and economic reforms have proven futile so far. That doesn't seem likely to change any time soon.

But that's an argument to dial up the pressure by outlining specific, painful consequences for Iraqi leaders who dither. It's not an excuse to hastily fold the tent.

Just as timetables for withdrawal were a guarantee of defeat, so, too, is a precipitous withdrawal with little heed to conditions inside Iraq. Gen. David Petraeus, the top commander on the ground, said recently that the violence can get "much, much worse" if American forces pull back from the Baghdad security mission. A National Intelligence Estimate this year similarly warned that "if coalition forces were withdrawn rapidly we judge that this almost certainly would lead to a significant increase in the scale and scope of sectarian conflict in Iraq."

The estimate predicted the Iraqi security forces "would be unlikely to survive as a nonsectarian national institution" and that neighboring countries might intervene openly; "massive civilian casualties and forced population displacement would be probable"; and al-Qaida "would attempt to use parts of the country to plan increased attacks in and outside of Iraq."

The potential for a cataclysm is so great that many of the same Iraqis who fervently wish American "occupiers" would leave also will grudgingly acknowledge that U.S. troops must stay, lest the violence grow worse.

© 2007 Chicago Tribune. Distributed by McClatchy-Tribune Information Services.