On the eve of the invasion of Iraq in 2003, many military officers and analysts predicted that US and coalition forces would have to fight their way into Baghdad and then conduct the kind of house-to-house urban warfare against Republican Guard and Fedayeen Saddam troops that is the most dangerous and the most deadly.
As it turns out, that didn't happen then. The invasion succeeded and Baghdad quickly fell, symbolized by the toppling of Saddam Hussein's statue.
Now, nearly four years later, American GIs are about to launch a new offensive in Baghdad that is very likely to be that kind of urban warfare, on a scale not yet seen.
The new strategy, though it anticipates a leading role for Iraqi forces, raises difficult and in some ways profound questions for the US military and its capabilities in the 21st century. After five years of fighting in Afghanistan and Iraq, does it have the resources and leadership to sustain an effort some experts say could take years, not months? And what's likely to be the long-range impact of this "surge" on the way the US military trains, equips, and plans for future conflicts?
Whether the plan outlined by President Bush will eventually succeed – and administration officials and supporters, as well as critics, say the odds are tough – the year ahead is likely to be "bloody and violent," as the commander in chief put it in his speech Wednesday night.
"Even if our new strategy works exactly as planned, deadly acts of violence will continue – and we must expect more Iraqi and American casualties," Mr. Bush said.
Administration war planners acknowledge that they can't predict how long the ramped-up effort to secure Baghdad will take.
"It's viewed as a temporary surge, but I think no one has a really clear idea of how long that might be," Defense Secretary Robert Gates said at a White House briefing Thursday.
"The US can sustain this escalation indefinitely, provided that there is an increase in end strength, longer and more frequent deployments, greater reliance on the guard and reserve, more money for recruitment and retention, and further lowering of standards for recruits," says John Pike, director of globalsecurity.org. "All of this will cost time and money."
Much depends on the nature of the enemy response. A long and violent battle in Baghdad this week, which lasted 11 hours and occurred not far from the protected Green Zone, may be a sign of things to come. "It was the most intense combat I have ever seen," an Army Stryker Brigade officer, in Iraq on his third tour, told The Washington Post.
The essence of the new strategy is the embedding of US forces with Iraqi units to go after enemy enclaves in Baghdad and the surrounding area.
White House officials insist that US forces will be strictly under US command.
"There is not going to be the opportunity for Iraqis to be giving direct orders to the United States," a senior administration official said at the White House before the president's speech.
But embedding also commits US troops to what could be a more complicated and longer-term engagement in Iraq.
"Like the proposal to use US forces to hold neighborhoods in Baghdad, embedding signals a sliding backward into greater US involvement rather than progress toward a self-sustaining Iraqi security system," says military analyst Loren Thompson of the Lexington Institute think tank.
While many military experts see the possibility of some successes, the greater challenges of counterinsurgency remain.
"If the tactics implementing this strategy are directed toward chasing and killing insurgents, which in turn require information from the population, the addition of 17,500 US troops will help," says retired Army Col. Dan Smith, referring to the five additional combat brigades going to Baghdad as part of the overall 21,500 troops that are Bush's total surge effort.
"But to gain the confidence of the Iraqi people, to convince them that the insurgents will not retaliate, requires developing a degree of trust that simply doesn't exist," says Colonel Smith, a military analyst with the Friends Committee on National Legislation in Washington.
Others note that even with the additional troops, the ratio of well-trained and reliable soldiers to Baghdad's population of 6 million is less than war planners say is needed to quell sectarian violence.
"He is adding just enough forces and publicizing it to make the Iraqi resistance rise to the challenge," says national security analyst Ivan Eland of the Independent Institute think tank. "He will also increase US casualties by embedding the troops with the Iraqis. US forces will no longer go back to their fortified bases at night. A previous increase in the forces ... led to increased resistance."
The president's new strategy for Iraq has a broader context – militarily and diplomatically.
One retired senior military officer looks at more forces going to the region, including Patriot missile batteries and equipment to counter antiship mines (neither of which would be useful against Sunni insurgents or Shiite militias in Iraq) and concludes that the Bush administration may have a broader agenda.
"The subtext of the speech tells me this is about Iran," says retired Air Force Col. Sam Gardiner.
Speaking to the House Armed Services Committee Thursday, Secretary Gates said he wants to increase the military by 92,000 soldiers and marines over the next five years, bringing the overall total to 202,000 marines and 547,000 Army soldiers.
"We should recognize that while it may take some time for these troops to become available for deployment, it is important that our men and woman in uniform know that additional manpower and resources are on the way," Gates said at a White House news conference.
But recruiting and training fresh troops may not relieve immediate problems, some analysts warn.
"The US military cannot sustain a higher level of commitment in Iraq without undercutting the capability to cope with crises in other places," says Mr. Thompson of the Lexington Institute. "Quick-reaction forces such as the 82nd Airborne Division are being tied down, and the whole force is being worn down. It is now obvious that the nation needs a bigger Army, but because the Bush administration failed to act years ago, there is no hope of generating usable recruits anytime soon."