Former Secretary of Defense Robert McNamara raised an issue in his 1995 book on the war in Vietnam that applies today in Afghanistan: What did the president and his senior advisers know about the country in which they intended to wage war before getting the United States deeply engaged?

McNamara, who passed away a month ago, said in "In Retrospect: The Tragedy and Lessons of Vietnam": "When it came to Vietnam, we found ourselves setting policy for a region that was terra incognita." He contended: "Our government lacked experts for us to consult to compensate for our ignorance."

Nonsense. The reservoir of experienced American officials, military officers, diplomats, scholars and others who knew much about Vietnamese history, culture and politics was shallow but wide enough to advise U.S. political leaders about what they were getting the nation into. All the secretary of defense had to do was to invite them to the Pentagon to give him a tutorial.

As former Secretary of State Colin Powell wrote in his book, "An American Journey," published the same year, Bernard Fall's book on Vietnam, "Street Without Joy," made "painfully clear that we had almost no understanding of what we had gotten ourselves into." Fall was a French correspondent who was killed in Vietnam in 1967.

Powell wrote: "I cannot help thinking that if President Kennedy or President Johnson had spent a quiet weekend at Camp David reading that perceptive book, they would have returned to the White House Monday morning and immediately started to figure out a way to extricate us from the quicksand of Vietnam."

The question today is whether President Obama, Secretary of Defense Robert Gates, Secretary of State Hillary Clinton, National Security Adviser James Jones and the special envoy on Afghanistan, Richard Holbrooke, have consulted with experts on Afghanistan as they plunge U.S. forces ever deeper into a country that has chewed up foreign armies for centuries.

Afghanistan is unlike most countries with which the U.S. has dealt in the last half-century. It has been a republic, a monarchy, a theocracy and a communist state. Its population has leapt from 13 million in 1979 to 33 million in 2009 despite decades of strife. The country is home to multiple ethnic groups: Pashtun, Tajik, Hazara, Uzbek, Turkmen, speaking 30 languages.

It is a tribal society in which loyalty to family, village and clan is stronger than that to nation. Disputes and perceived violations of personal honor are often settled with violence. Literacy among men is 51 percent, among women 21 percent, another indication of a deep split in Afghan culture.

Specialists on Afghanistan, however, often disagree. Seth Jones of the RAND research corporation was quoted in Newsweek: "It's a complete pipe dream to expect that an Afghan central government can establish order and deliver key services on its own."

But Peter Bergen, a journalist, contended in the Washington Monthly: "Modern Afghanistan is considered to have emerged with the first Afghan empire under Ahmad Shah Durrani in 1747, and so has been a nation for decades longer than the United States. Accordingly, Afghans have a strong sense of nationhood."

President Obama and his advisers should not be faulted for inattention to Afghanistan. In presidential rhetoric, revised strategy and meetings with foreign leaders, the administration has given a high priority to the Afghan issue.

Perhaps the key statement was Obama's on March 27: "We are in Afghanistan to confront a common enemy that threatens the United States, our friends and our allies, and the people of Afghanistan and Pakistan who have suffered the most at the hands of violent extremists."

That, however, does not reveal whether the administration is setting policy for a land that Robert McNamara might have called "terra incognita."

Richard Halloran, formerly a New York Times correspondent in Asia and in Washington, is a writer in Honolulu.