Even before Congress got an encouraging update on security in Iraq from Gen. David Petraeus, some senators and congressmen kept urging that the United States rush for the exits with a quick pullout of troops.

It doesn't seem to matter to those who've decided on defeat, but Gen. Petraeus, the unanimously confirmed U.S. commander in Iraq, documented that his "surge" of troops achieved significant security gains and reductions in violence over the summer.

And it doesn't seem to faze the naysayers that Ambassador Ryan Crocker, while openly sharing their frustration with slow political progress, testified firmly that "a secure, stable, democratic Iraq" remains "attainable."

These critics woefully, if not willfully, continue to underestimate the umbrella of security U.S. troops provide for the advance of freedom in Iraq.

Democrats and other detractors of the mission aren't going to be satisfied with Petraeus' expectation -- embraced within hours by President Bush -- that he gradually could withdraw the surge's extra 30,000 troops by next summer, beginning with 2,000 this month.

That would leave about 130,000 troops in Iraq as the general assesses further progress.

Last spring, remember, Congress passed legislation that would have "redeployed" most of those troops outside Iraq, essentially limiting their mission to pursuing al-Qaeda terrorists or training Iraqi security forces. The legislation, correctly vetoed by the president, stated that remaining U.S. forces in Iraq would be permitted only to protect unspecified "American diplomatic facilities and American citizens."

The troops surely would protect the U.S. Embassy and diplomatic personnel. But what about the safety of non-governmental organizations (NGOs) working to strengthen Iraq's nascent democracy, such as the International Republican Institute and the National Democratic Institute, not to mention their many Iraqi employees? What about the Provincial Reconstruction Teams operating throughout Iraq?

Brave civilians are risking their lives to establish good governance, the rule of law and human rights. The U.S. Agency for International Development, for example, has trained more than 8,000 national, regional and local officials in concepts that were meaningless under Saddam Hussein: government transparency and accountability, fiscal responsibility, and human dignity.

These civilian efforts, in addition to supporting elections across Iraq, include projects to expand political and civic participation; guarantee the rights of women; encourage religious tolerance; establish an independent media; foster good governance and limit corruption.

All these strides toward strengthening Iraq's civil society will be for naught if the U.S. precipitously withdraws troops.

Extremist-fueled sectarian violence, we already know, threatens to erupt into a full-scale civil war between Sunni and Shiite Muslims that would consume all of Iraq and engulf its neighbors in a regional conflict. The stream of Iraqis seeking refuge in Jordan, Egypt and elsewhere - already including about 40 percent of the middle class -- could grow into a wholesale exodus.

An early U.S. military exit likely would result in the collapse of the Iraqi central government, its armed forces and other institutions. Concepts like democracy, human rights, the rule of law and individual freedom will fall fast in the wake of chaos and anarchy.

Citizens of Tikrit, Saddam's hometown, wrote hundreds of letters of protest early this year when one NGO, the National Democratic Institute, decided to close its resource center there until violence could be quelled. But advancing democratic ideals in their towns won't be such a priority for ordinary Iraqis if a U.S. military withdrawal leaves their very survival at stake.

Will Congress call for us to return to Iraq after the resulting humanitarian crisis claims hundreds of thousands of lives?

Patience from Congress and the American people will permit U.S. forces to complete their mission to secure Baghdad and formerly "lost" provinces such as Anbar, where President Bush made his richly symbolic Labor Day visit to troops. Petraeus and Crocker, unflinching in acknowledging the hard road ahead, described how our forces are reclaiming turf, newly rallying local support and taking down the terrorists who want to destabilize Iraq and subjugate or kill those who thirst for freedom.

The United States bears a responsibility to leave Iraq in better condition than it was before our military coalition toppled Saddam's regime. A stable and secure Iraq -- where a free and fair democracy can thrive -- can't emerge until the various Iraqi factions reconcile. The surge remains the best hope to provide a safer environment for such accommodation to take place, and that's unquestionably happening on the local level.

To abandon the Iraqis in their time of need is to condemn them to chaos, an endless cycle of bloody retaliation, the rebirth of a Saddam-style authoritarian government -- or worse.

Steven Groves oversees the Freedom Project as the Bernard and Barbara Lomas Fellow of the Margaret Thatcher Center for Freedom at The Heritage Foundation (heritage.org).