Washington (CNN) -- While President Obama's war council deliberates its strategy toward Afghanistan, the ghost of Vietnam is often invoked as a warning.

Afghanistan, U.S. and coalition forces have been fighting in Afghanistan for eight years, and until recently the war had been overshadowed by the one in Iraq. In March, Afghanistan will become America's longest war, surpassing the Vietnam War.

The Vietnam War, which cost 58,000 American lives, is the one most often invoked when U.S. troops are committed overseas.

Although some say Afghanistan is "Obama's Vietnam," experts say there are several major similarities and differences between the two wars.

Eric Margolis, a veteran journalist and former Army soldier who served during the Vietnam War, said the biggest problem the United States is facing now -- as in Vietnam -- is fighting the mostly poor, rural insurgents who live among Afghans.

"It makes it very difficult to drive [insurgents] out, because they can stay there forever. ... They're at home. When we attack villages where they are, we kill a lot of civilians, causing an uproar and turning the people more against us."

Steve Clemons of the nonpartisan New America Foundation said one of the factors in the Soviet-Afghan War -- which pitted the Soviet-backed Democratic Republic of Afghanistan with the Soviet military against the Islamist Mujahideen Resistance -- was the brutal attacks inflicted on both fighters and civilians by the Soviets.

"[There] was the sense of outrage and grievance at some of the things that they had done and the triggering of a deeply felt emotional antagonism to the Soviet effort to dominate and colonize Afghanistan among the Pashtun."

He worries that if the United States fails to focus on a more humanitarian and diplomatic approach, Americans will fall into the same trap the Soviets faced, which ultimately led to them leaving the country defeated.

"I think one of the things I'm concerned about is whether or not we're triggering those same kind of emotions among the Pashtuns today. And believe me, the Pashtuns don't care whether they're [going after] Americans or going after the Soviets. If you begin to threaten their own perception of their own independence, then you turn Pashtuns into Taliban."

Peter Beinart, who recently wrote an article called "Bury the Vietnam Analogy" on TheDailyBeast.com, has said there is a real sense of national identity for Afghanis that wasn't seen in South Vietnam.

"Afghanistan is a real country that Afghans generally believe in. They have an Afghan national identity. That didn't exist in South Vietnam," he said, adding that the Taliban is much less popular in Afghanistan than the Viet Cong was in South Vietnam.

In Vietnam, the Communists controlled the nationalist movement and had the nationalist legitimacy. The Taliban, meanwhile, is not as organized as the Viet Cong and North Vietnamese army were.

But there is evidence the Taliban is changing, as shown by a series of recent well-coordinated attacks on remote Afghanistan outposts.

Journalist Margolis also compared the government of Afghanistan to the government of South Vietnam.

"In both cases, the government of Saigon [South Vietnam] and Kabul [Afghanistan] are heavily influenced by minorities. We have made our enemies [among] the ethnic majority in Afghanistan who are the Pashtuns -- pretty well cut them out of power."

The recent Afghanistan elections received worldwide attention for claims of fraud by the incumbent, President Hamid Karzai, who reportedly won the election. After fierce international criticism, Karzai recently agreed to a runoff.

Another difference between the two wars comes in terms of troop numbers, Beinart said.

"I think what's clear is that the resources we put in Afghanistan have been absolutely minuscule compared to Vietnam and compared to Iraq. ... In 1968, we had over 500,000 U.S. troops in South Vietnam. We had up until a couple of years ago only about 20,000 [in Afghanistan]. ... So what's clear is, we haven't made anywhere near the kind of commitment to Afghanistan as we made to Vietnam."

In the past month, Obama's top commander in Afghanistan, Gen. Stanley McChrystal, issued a report to the president and the administration, outlining the problems facing the nation and what resources will be needed. His prescription: more troops -- upwards of 40,000 by some estimates -- with the goal focusing on securing Afghan towns and cities in certain areas.

"And McChrystal's request, that we need to actually protect the Afghanis in this situation as opposed to just go after and try to kill bad guys on the other team, is a very different approach than Vietnam and I don't think has received enough attention," Clemons said.

One of Obama's biggest critics recently lashed out over the president's deliberations on how to proceed in Afghanistan.

Former Vice President Dick Cheney said last week that Obama has failed to give troops on the ground a clear mission or defined goals and appeared "afraid to make a decision."

"The White House must stop dithering while America's armed forces are in danger," he said. "Make no mistake, signals of indecision out of Washington hurt our allies and embolden our adversaries."

But on Sunday, a top Republican beat back against such criticism.

Sen. Orrin Hatch of Utah said he thought some of Obama's critics have been "hypercritical" in suggesting that the president was delaying a decision about Afghanistan.

Appearing on CNN's "State of the Union" on Sunday, Sen. Jim Webb, D-Virginia, also defended the president, saying he is using a "very proper and smart process" in taking time to weigh all options on the table.

And public opinion may be part of the reason: There is declining support among Americans over sending more troops.

A CNN/Opinion Research Corp. poll, taken October 16-18, showed 59 percent of Americans opposed sending more troops into the country. The same poll found that 52 percent of Americans consider the war in Afghanistan has turned into another Vietnam War situation, while 46 say it's not.

The poll had a margin of error of plus or minus 3 percentage points.