What are the right lessons from America’s Vietnam experience that can be applied to the current situation in Iraq and elsewhere in the Middle East?

The United States in the 1960s and early 1970s found itself backing a shaky South Vietnam government that lacked full support from religious and sectarian groups within its borders as it faced armed Viet Cong insurgents. Today it’s the newly formed, Shiite-dominated government of Prime Minister Haider al-Abadi in Baghdad facing Islamic State fighters without the total support of some Iraqi Sunni, Kurd and secular groups.

In Vietnam, the insurgents were fed arms, supplies and even fighters from North Vietnam through nearby Laos and Cambodia. Today, equipment, supplies and Islamic State fighters come into Iraq through neighboring Syria.

The South Vietnamese military was further weakened by corruption and lack of training. The Iraqi security forces have the same problems.

The surprising Islamic State takeover this month of the Iraqi city of Ramadi, capital of Sunni-dominated Anbar province, has triggered questioning of the Obama administration’s policy and led to new comparisons with Vietnam.

Anthony Cordesman, a former senior Pentagon official and now a military analyst with the Center for Strategic and International Studies (CSIS), wrote on Thursday that he believes one key lesson from Vietnam for Iraq should be stepped-up U.S. military involvement.

On the CSIS Web site, Cordesman called for embedding Americans with Iraqi fighting units.“Insurgents cannot be allowed to have a massive intelligence advantage on the ground, to learn the weakest links in the government forces and their defense,” he argued.

“New and weak [Iraqi] units need to have a small, but experienced team of [U.S.] combat leaders embedded with them,” he added, noting that “forward deployed train and assist teams — usually special forces or rangers — are necessary to spot good combat leaders and warn against weak, ineffective, or corrupt ones.”

Cordesman is far from alone. Sens. Lindsey Graham (R-S.C.) and John McCain (R-Ariz.) and others have called for a larger U.S. presence.

I disagree. The Vietnam experience showed that when dealing with such situations the provision of additional American personnel to “train and assist” can easily and perhaps inevitably lead to sending more forces to do the actual fighting.

Vietnam started out that way under President John F. Kennedy, when in May 1961 he sent 400 American Green Berets to South Vietnam to train that country’s military in counterinsurgency. Five months later, Kennedy was advised to raise the number to 8,000 and include combat forces.

I worked for 18 months in the late 1960s for Sen. J.W. Fulbright (D-Ark.) when the then-chairman of the Senate Foreign Relations Committee was investigating the Vietnam War. He told me more than once how President Lyndon Johnson in 1964 said that if Fulbright agreed to support authorization for 125,000 U.S. combat troops in Vietnam, that would be enough to win the war.

Five years later, with over 500,000 U.S. forces fighting there, the Vietnam War still was not won.

In fact, the U.S. lost 58,220 lives trying to defeat a communist-led North Vietnamese enemy. Today, a successor communist government not only controls all of Vietnam but is on friendly terms with Washington.

That should be a key lesson from Vietnam. Foreign governments have to find their own way.

Cordesman, however, is right about several things. He is correct when he says, “We are dealing with a range of extremist movements and an ideological struggle for the future of Islam,” and that “no kind of lasting ‘victory’ in the form of some reasonable degree of stability and security can occur in Iraq — or any of our other wars — without effective national unity.”

Vietnam should have taught the U.S.that as an outside power — with no common language, culture or history — Americans cannot bring about national unity in other countries.

Cordesman makes another point worth remembering in the Vietnam context — there will be no peace in Iraq, even with national unity, if across the border in Syria there is a sanctuary for Sunni forces hostile to the government in Baghdad.

There is one final point that Cordesman makes that the Obama administration, Congress and presidential candidates should take to heart.

“We need regular, honest, and comprehensive Obama administration reporting on the course of our wars,” he writes. He adds that also needed are “hearings and congressional reviews that do more than focus on five minute media visibility exercises for committee members.”

“Far more congressional action is needed than vague calls for ‘strategy,’ ” Cordesman writes. He also hits at “even vaguer partisan attacks that are designed to target the coming election or promote a particular Republican presidential candidacy.”

In the wake of Ramadi, a different approach, “containment,” has been offered by Dov S. Zakheim, another former senior Pentagon official who is now a military analyst.

He wrote Saturday on the National Interest Web site that post-Ramadi, Washington’s long hope that the Islamic State could be defeated without American boots on the ground “has been proved once and for all to be a quixotic pipedream.” But, he added, “America will not dispatch the hundreds of thousands of troops required both to defeat [the Islamic State] and pacify Iraq and Syria.”

That leaves ending the Islamic State, according to Zakheim, to “its regional antagonists . . . or wait until it implodes, as inevitably it will.”

Zakheim’s containment plan calls for the U.S. to maintain “the current web of uneasy partnerships,” meaning air support, arms and training for the Iraqis, as well as the Kurds in northern Iraq and northeastern Syria.

Defense Secretary Ash Carter summed up Sunday on CNN what the Vietnam lesson should be. “If we give them training . . . equipment . . . support and give them some time, I hope they will develop the will to fight, because only if they fight can [the Islamic State] remain defeated.”

For previous Fine Print columns, go to washingtonpost.com/fedpage.