The Vietnam War was a tragic mistake and disaster for the U S.  As a result, in 1984, the U S government announced what is called the Weinberger Doctrine.

1. The United States should not commit forces to combat unless the vital national interests of the United States or its allies are involved.
2. U.S. troops should only be committed wholeheartedly and with the clear intention of winning.  Otherwise, troops should not be committed.
3. U.S. combat troops should be committed only with clearly defined political and military objectives and with the capacity to accomplish those objectives.
4. The relationship between the objectives and the size and composition of the forces committed should be continually reassessed and adjusted if necessary.
5. U.S. troops should not be committed to battle without a ‘reasonable assurance’ of the support of U.S. public opinion and Congress.
6. The commitment of U.S. troops should be considered only as a last resort.

It is difficult to see any of those criteria being met in the war commenced by Donald Trump in Iran.  (He is not allowed to declare war.)  One result is described in the following insightful article.

Wall Street Journal Article on the Fears of Trump

It seemed like Donald Trump’s appetite for risk had run out, and his fears were ramping up.

It was Good Friday afternoon in a nearly empty West Wing soon after the president learned that an American jet had been shot down in Iran, with two airmen missing. Trump screamed at aides for hours. The Europeans aren’t helping, he said repeatedly. Gas prices averaged $4.09. Images of the 1979 Iranian hostage crisis—one of the biggest international policy failures of a presidency in recent times—had been looming large in his mind, people who have spoken to him said. 

“If you look at what happened with Jimmy Carter…with the helicopters and the hostages, it cost them the election,” Trump had said in March. “What a mess.” 

Trump demanded that the military go get them immediately. But the U.S. hadn’t been on the ground in Iran since the government overthrow that led to the hostage crisis, and they needed to figure out how to get into treacherous Iranian terrain and avoid Tehran’s own military. Aides kept the president out of the room as they got minute-by-minute updates because they believed his impatience wouldn’t be helpful, instead updating him at meaningful moments, a senior administration official said.

An image posted on Iran’s Islamic Revolutionary Guard Corps official Telegram channel appears to show a U.S. transport plane and two helicopters destroyed during a rescue mission to locate one of the U.S. airmen.

One airman was recovered quickly, but it wasn’t until late Saturday that Trump received word that the second airman had been rescued in a high-stakes extraction. What could’ve turned into the lowest point in Trump’s two terms, wouldn’t. After 2 a.m., Trump, too, went to bed. 

Six hours later, the chest-thumping president was back with another audacious gamble to loosen Iran’s grip on its most powerful point of leverage, the Strait of Hormuz. “Open the Fuckin’ Strait, you crazy bastards, or you’ll be living in Hell,” he blasted on social media Easter morning from the White House residence, adding an Islamic prayer to the post. 

A president who thrives on drama is bringing an even more intense version of his unorthodox, maximalist approach to a new situation—fighting a war. He is veering between belligerent and conciliatory approaches and grappling behind the scenes with just how badly things could go wrong.

At the same time, the president sometimes loses focus, spending time on the details of his plans for the White House ballroom or on midterm fundraisers—and telling advisers he wants to shift to other topics. 

Trump is dealing with his own fear about ordering troops into harm’s way where some will be injured and some not return home, similar to other presidents who have been at war, people familiar with the matter said. 

Trump has resisted sending American soldiers to take Kharg Island, for example, the launch point for 90% of Iran’s oil exports. While he was told the mission would succeed, and the territory’s capture would give the U.S. access to the strait, he worried there would be unacceptably high American casualties, the people said. They’ll be sitting ducks, the president said. 

Still, he has made risky pronouncements without input from his national security team—including his post about plans to destroy the Iranian civilization—saying seeming unstable could help spur the Iranians to negotiate.

At one point he even mused he should award himself the nation’s highest military honor, the Medal of Honor.

Trump campaigned on ending foreign wars but wagered that he could solve, with American air and naval power, a national security problem that had bedeviled seven previous presidents. Now, a cease-fire is in doubt, a critical trade route has been closed for weeks and Iran’s regime has been replaced with radical new leaders, all threatening to lengthen an operation that Trump has repeatedly said would only last six weeks—a deadline already missed since the war began Feb. 28.

White House officials said they believe a breakthrough in negotiations with Iran could be reached in coming days, and they are eyeing more talks in Pakistan.

The president’s impulsive style has never before been tested during a sustained military conflict. Unlike the successful operation in Venezuela, which buoyed his confidence, Trump is confronting a more intractable foe in Iran, which is so far unwilling to bend to his demands. 

“We are witnessing astonishing military successes that do not add up to victory and that is squarely on the president and how he’s chosen to do his job—lack of attention to detail and lack of planning,” said Kori Schake, a senior fellow at the right-leaning think tank American Enterprise Institute who served on former President George W. Bush’s National Security Council.