United States President Donald Trump has promised if it comes to war, the US will "have no choice but to totally destroy North Korea".

Tough words from a trash-talking President. But he's forgotten one thing. Historically, when America is the one that picks the fight, it loses.

So while Trump threatens North Korean dictator Kim Jong-un that "Rocket man is on a suicide mission for himself and for his regime," historians hope that if the worst happens and war breaks out, it's not the US that fires the first shot.

It's a record highlighted by online US media website Defense One in a recent article by author, defence adviser and former naval officer Harlan Ullman, who lays the blame squarely at the feet of successive American presidents.


And he warns, Trump may prove the worst of them when it comes to "strategic judgment and understanding".

The comments come after North Korea's state media last week proclaimed a death sentence on Trump for insulting Jong-un by calling him "short and fat".

Writing about his new book Anatomy of Failure: Why America Loses Every War It Starts, Ullman said Americans believe their military is the best in the world, and while the US won the Cold War, its record since World War II isn't exactly a success story.


"Every time Americans were sent to wars that it started or into combat for reasons that lacked just cause, we lost or failed," said Ullman, who commanded a destroyer in the Persian Gulf, led more than 150 missions and operations in Vietnam, and is a senior adviser on US defence policy to Washington's Atlantic Council.

A man watches a TV screen showing file footage of North Korea's missile launch in August. Photo / AP
A man watches a TV screen showing file footage of North Korea's missile launch in August. Photo / AP

"Korea was at best a draw, ended not by a peace treaty but a "temporary" truce.

"Our record in subsequent conflicts was too often no better, and too often worse.

"Vietnam was an outright and ignominious defeat in which over 58,000 Americans died."

He said while America deserved "great credit" in the first Iraq War and in handling the collapse of the Soviet Union, "the Afghanistan intervention begun in 2001 is still going with no end in sight".

Ullman's scathing attack continued: the Second Iraq War, launched in 2003, was "rightly termed a fiasco" and "smaller interventions - Beirut and Grenada in 1983, Libya in 2011 - failed".

He laid the blame not at the feet of the Pentagon, the US centre of military defence, but at the White House and successive presidents.

"Failure begins at the top. Americans elect presidents who, too often, are unprepared, unready and too inexperienced for the responsibilities of arguably the most difficult office in the world," Ullman said.

"This has led to flawed strategic judgment made worse by an absence of sufficient knowledge and understanding of the conditions in which force is to be used."


He said the US must discard its 20th-century thinking to avoid future wartime failures.

"Tragically, the US started these wars for reasons that proved wildly wrong, or intervened based on lack of knowledge and understanding that led to failure," Ullman said.

"While Donald Trump, fortunately, has not suffered a crisis such as 9/11, his strategic judgment and understanding seem as poor as or even worse than his predecessors."

As Trump and Kim trade threats, the tense stand-off over North Korea's development of nuclear-tipped missiles capable of hitting the US continues to see the world fear it is teetering on the brink of war.

At the weekend, the US's top nuclear commander said if Trump ordered a nuclear attack he disagreed with, he would refuse.

General John Hyten said he wouldn't drop a nuclear bomb if he thought Trump's order was illegal.

Hyten told an audience on Saturday at the Halifax International Security Forum in Nova Scotia that he's thought a lot about what he will do if Trump orders a strike he considers illegal.

But, he said, if the command was "illegal" he would tell the President that, and said together they would come up with other options.

Meanwhile, Ullman said US policymakers needed to develop "far greater knowledge and understanding of conditions in which force is to be used".

"Unless and until Americans recognise why we fail too often in using force and correct these flaws, the chances of future reverses may not be inevitable. But it is highly likely," he said.