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As I’ve listened to President Obama speak about the war against Islamic State (ISIS) and his pledge not to “commit U.S. troops to another ground war in Iraq,” I had an uncomfortable sense of déjà vu.

Maybe it is my age and generation, but I kept hearing another president.

Fifty years ago this week, on Sept. 25, 1964, Lyndon Johnson told the nation, “We don’t want our American boys to do the fighting for Asian boys. We don’t want to … get tied down in a land war in Asia.” He was talking about Vietnam.

On that day, I was a Ph.D. student at Ohio State University; six weeks later I was a Pfc. in the U.S. Army at Fort Knox, Ky.

It was eerily familiar when Obama said, “We cannot do it for them”; we will train, equip, assist and advise them, but they will have to do the fighting themselves.

We started out in Vietnam with advisers, equipment and assistance. We wound up with more than 55,000 dead Americans and many times that number maimed and wounded. More recently the Bush-Cheney administration launched an unnecessary war based on lies to settle an old score with Saddam Hussein, and wound up creating a pro-Iranian Shiite government that was closer to Tehran than Washington despite the fact that we put them in power and paid them.

Actually, the potential for miscalculation and disaster is even greater in this war against ISIS than in the Vietnamese conflict. Back then, we were facing a typical communist insurgency; while we grossly underestimated both the military strength of our adversaries and their popular support, we knew the enemy. ISIS is a far more amorphous enemy, a surging, ever-changing movement tied to ancient religious and tribal grievances. Going to war against an enemy we don’t understand vastly multiplies the risks of national catastrophe.

As we bombed Vietnamese villages to “save” them from the communists, we only increased support for Hanoi; what reason do we have for believing things will be different in the Middle East, where America is already viewed as a mortal enemy?

What will happen — as it inevitably will — when some of those U.S. forces are killed or kidnapped? Won’t the pressure be almost irresistible to invest even more heavily in an unwinnable conflict? Obama may indeed oppose the insertion of American troops into the conflict, but history suggests such intentions are quickly abandoned

One rationale for this new war also has a familiar ring: the old domino theory. Remember when we were told if South Vietnam fell to the hands of the communists the rest of Southeast Asia would be sure to follow? Now it’s Syria, followed by Lebanon, Iraq, Jordan and the rest of Southwest Asia.

The Shiite-dominated government of Iraq, despite owing its existence to the United States, refused to let us keep forces in Iraq. Had we been able to leave several thousand forces behind, we might have been able to ensure that the Iraq army could prevent or at least defeat ISIS.

Instead, the Iraqi army that we had trained and equipped shed its uniforms, ran at the first sign of danger and dropped its arms. What makes anyone think it will be different this time?

The president promised no American boots on the ground, but on Sept. 16 his chairman of the Joint Chiefs of Staff opened that door a crack. And if you’ll indulge my metaphors, the other side of that door is a very slippery and dangerous slope.

Actually, there already are American boots on the ground, about 1,700 advisers, but no combat troops. Yet.

Congress quickly approved — and the president signed — spending $500 million to train and equip moderate Syrian opposition forces, as soon as some moderates can be found.

This is something the Saudis and their oil-rich neighbors should be paying for since they’re the primary beneficiaries of halting ISIS. American taxpayers already plunked down over a trillion dollars to “liberate” Iraq and defend the gulf, sacrificed nearly 5,000 lives and injured many thousands more Americans.

The president has been at the United Nations this week recruiting world leaders to join his “coalition of the willing,” but few are terribly willing. The White House says it already has many successful partners but isn’t naming them or the role they’ll be playing.

Most disturbing, our NATO ally, Turkey, which has a border with Iraq and Syria and may face a serious threat from ISIS, has refused to help as of press time. Turkey’s Islamist government, as in the 2003 Gulf War, has not allowed our planes to use NATO bases or its territory or air space. This is all the more egregious because Turkey is a major source of recruits and funds for ISIS; it’s unclear what, if anything, the Erdogan government is doing to stop that.

Douglas M. Bloomfield is the president of Bloomfield Associates Inc., a Washington, D.C., lobbying and consulting firm. He spent nine years as the legislative director and chief lobbyist for AIPAC.