War is never by the books. Adversaries learn and adapt. The political climate shifts on both sides. Loyalties and alliances couple and decouple. The civilian populace - caught in the crossfire - often remains passive just to survive.
To many experts, the conflict in Iraq has entered a new phase that resembles a classic guerrilla war with US forces now involved in counterinsurgency. And despite the lack of ideological cohesion among insurgent groups, history suggests that it could take as long as a decade to defeat them.
"Guerrilla warfare is the most underrated and the most successful form of warfare in human history," says Ivan Eland, a specialist on national security at the Independent Institute in Oakland, Calif. "It is a defensive type of war against a foreign invader. If the guerrillas don't lose, they win. The objective is to wait out your opponent until he goes home."
From the Filipino insurrection during the Spanish-American War to Vietnam to El Salvador, American troops have had plenty of experience in fighting home-grown enemies that look nothing like a conventional army. As have France in Algeria, Britain in Malaysia and Northern Ireland, Israel in the occupied territories.
Though "counterinsurgency" calls up memories of Vietnam, there may be as many differences as similarities.
Iraqi insurgents have no means of deploying battalion-size forces, as North Vietnam and the Viet Cong did with help from the former Soviet Union. Iraq won't become a proxy conflict between superpowers, as the Vietnam War was. There is a heavy criminal dimension to the violence in Iraq, just as there has been in Algeria, Colombia, and Chechnya. And there is unlikely to be a negotiated resolution as long as Iraq is seen as part of the broader war on terrorism.
Still, Iraqi insurgents have the advantage of terrain - not jungles but an urban setting. They appear to have at least the passive support of many Iraqis. It's often difficult to tell the fighters from innocent civilians. And they try to force American forces to overreact, causing civilian casualties and consequent outrage.
"No two insurgencies are alike," says retired Army Col. Dan Smith of the Friends Committee on National Legislation. "Except that they are violent affairs in which noncombatants tend to suffer most and national infrastructure tends to be destroyed."
Since early April, when the health ministry in Baghdad began keeping figures, some 3,200 civilians (not including Iraqi police or insurgents) have been killed - some in terrorist attacks, some by the US-led coalition. On average, insurgents now are attacking US forces 87 times a day. More than 100 foreigners have been kidnapped, and some 30 of those killed. Attacks on oil pipelines are occurring nearly every day now.
In fact, Iraq at the moment has four simultaneous insurgencies: Sunni tribalists, former Saddam regime loyalists, fighters loyal to anti-US cleric Moqtada al-Sadr, and foreign jihadists.
"Most importantly, the insurgents haven't made much effort to develop a coherent political program or identify a leadership," says Professor Steven Metz of the US Army War College. "I see this as their most serious weakness."
Still, they do have a common enemy: those they see as foreign occupiers, not liberators.
Within the US military, much of the debate over how to deal with insurgencies revolves around one assertion: "No more Vietnams."
Army Lt. Col. Robert Cassidy, who has served in Iraq and is now stationed in Germany, notes that the US military "has had a host of successful experiences in counterguerrilla war, including some distinct successes with certain aspects of the Vietnam War."
But, he writes in a recent issue of the Army journal Parameters, "Because the experience was perceived as anathema to the mainstream American military, hard lessons learned there about fighting guerrillas were neither embedded nor preserved in the US Army's institutional memory."
"Unconventional war" in fact has been studied, trained for, and practiced for more than 40 years. But fighting guerrillas doesn't necessarily allow for the best use of the largest, most technologically advanced armed force in human history. Nor does it always address the real basis for defeating an insurgency, which rests more on political, cultural, and economic factors. Other militarily dominant countries have learned this as well.
"In many aspects, the French counterinsurgency effort typified the frustrations faced by modern powers in a classic unconventional conflict," states a US Marine Corps training document. "Like the US in Vietnam, the French in Algeria were unable to transform military successes (of which there were many) into a political victory."
Defense analyst Loren Thompson of the Lexington Institute sees two basic defects in the US-led counterinsurgency campaign in Iraq today.
"First, policymakers wrongly assume that Sunni Arabs can be induced to join in a democratic government where they are assured of permanent minority status," says Dr. Thompson, who supported the US invasion of Iraq. "Second, policymakers insist on viewing violence through the prism of the war on global terrorism, which obscures the sources of conflict and requirements for victory." Thompson's controversial answer would be to partition Iraq into three countries: Sunni Arab, Shiite Arab, and Kurd.
That US military planners did not adequately plan for an organized Iraqi resistance that would become an insurgency reflects a way of thinking that has often afflicted governments and militaries, says RAND Corp. analyst Bruce Hoffman, who spent a month this year in Baghdad advising the Coalition Provisional Authority on counterterrorism and counterinsurgency.
What this amounts to, writes Dr. Hoffman in a recent RAND paper, is "the failure not only to recognize the incipient conditions for insurgency, but also to ignore its nascent manifestations and arrest its growth before it is able to gain initial traction and in turn momentum."
With the insurgency apparently gaining traction and momentum, such criticisms now are coming from prominent Republicans in Congress. "The lack of planning is apparent," Senate Foreign Relations Committee chairman Richard Lugar (R) of Indiana said last week. Sen. Chuck Hagel (R) Nebraska, a decorated infantry squad leader in Vietnam, says the recently announced shifting of reconstruction funds to security is "an acknowledgment that we are in deep trouble."
Classified British documents, reported in the Daily Telegraph newspaper over the weekend, warned a year before the invasion of Iraq that even if a democratic government could be created there, "it would require the US and others to commit to nation-building for many years" and that this would "entail a substantial international security force."
Even if the insurgents dwindle to a handful of terrorists, their impact on security and stability in Iraq could far outweigh their numbers. RAND's Hoffman points out that just 20-30 members of the Baader Meinhof Gang terrorized the former West Germany for two decades; 50-75 Red Brigadists did the same in Italy; and some 200-400 IRA gunmen and bombers required the prolonged deployment of tens of thousands of British troops in Northern Ireland.
Is it possible to prevail over the Iraqi insurgency?
First, says John Pike of the group GlobalSecurity.org, enemy combatants must be killed, captured, or demoralized faster than new ones can be recruited, and the majority of the population must come to see the insurgency as illegitimate and its defeat as inevitable.
It's a tough job, one that's likely to take years - as long as 10 years, says Dr. Metz at the Army War College. And the outcome is by no means assured.
"The government must appear to be legitimate, inevitable, and effective at providing security and services," says Mr. Pike. "As long as Iran does not stir the pot, these objectives could be approached by the end of this decade, with luck."