Successfully ending the festering insurgencies in Fallujah and Najaf in the upcoming days could be the most important event of the entire Iraqi campaign.

Terminating these bold-faced symbols resistance could send the insurgents, terrorists and their supporters reeling, undermine their recruiting of Iraqis and foreign jihadists and keep the June 30 political transition to Iraqi sovereignty on track.

Failure could embolden the insurgents and terrorists, lead to more violence and reconstruction disruptions, delay the return to Iraqi rule and diminish the Iraqis'-and the world's - confidence in the Coalition.

Arguably, the political and military stakes embodied in these thorny standoffs couldn't be greater either in Iraq - or here at home. The fact that President Bush consulted with his top national security advisers and military commanders in Iraq over the weekend to consider what to do specifically about Fallujah and Najaf is evidence of how critical these matters are.

Of course, the situation doesn't have to come to blows in Fallujah and Najaf. A negotiated settlement is still possible and preferable to sending our troops into harm's way. An agreement would be ideal if it leads to the surrender of the terrorists and the insurgents, including radical Shiite cleric Muqtada al-Sadr and the killers of the four American contractors in Fallujah.

In fact, the very threat of serious military force could bring the militants to the negotiating table - but, unfortunately, it's unlikely.

If the Fallujah civic leaders can't get the insurgents to turn in their heavy weapons as a first step, American and Iraqi troops will likely start to put military pressure on the Sunni city of 200,000. If military action is required, civilians should be encouraged to leave the city in advance of a full-court press by the Marines and Iraqi forces. (One-third of the city has fled since the siege began April 5th.)

In Najaf, American and Iraqi troops will likely have to enter the city to crack down on Sadr and his Shi'a al-Mahdi militia. Fighting in Najaf is more complicated than Fallujah because of the sensitivity of Najaf's Shiite holy sites. There is a strong possibility of stirring up religious outrage among Iraq's Shi'a majority (60 percent of Iraqis are Shiite) just by entering the holy city itself.

Violating a holy site is another matter altogether. Of course, if a holy site is used for military purposes, it's no longer a holy site - it becomes a legitimate military target. Getting rid of Sadr and disassembling his alliance with his Iranian supporters is critical to pacifying the Shi'a South.

But standby for some heavy weather if Coalition forces move into Fallujah and Najaf to root out the insurgents and their terrorist allies.

Hopefully the resistance would crumble quickly, but the fighting could turn ugly and rapidly become reminiscent of the street fighting seen in the movie "Black Hawk Down" or the last minutes of "Saving Private Ryan." Door-to-door, urban warfare can be nightmarish. If it does comes to a military showdown in Fallujah and Najaf:

* Use Iraqi forces to the greatest extent possible. This is their fight as much as - if not more than - ours. We should be using them wherever we can and accelerating the training of other Iraqi forces for counterinsurgency operations as soon as possible. It's time for Iraqi soldiers to earn their battle stripes in fighting for their country. We've certainly earned ours.

* Employ overwhelming force. There has been plenty of debate about the number of American troops in Iraq. It seems we need an upsurge in troops there and the commanders should have them, especially for these operations.

We should use maximum violence to end these insurgencies if necessary, but we should be careful to avoid civilian casualties to the extent possible. We need to keep as many Iraqi hearts and minds on our side as we go forward.

Security and stability is critical to moving forward in Iraq and getting a handle on Fallujah and Najaf is fundamental to doing so. Even if these standoffs are resolved successfully, dustups with the bad guys will happen from time to time, but, in the meantime, the Coalition has to show the insurgents, terrorists and their supporters - inside and outside Iraq - who's the boss.

Heritage Foundation Senior Fellow Peter Brookes spent some of his days at the CIA working on Central Asian issues. E-mail: [email protected] .