Whether negotiating skyscraper deals or conducting a trade war with China, Trump can resemble a flamboyant and highly unpredictable poker player.

As he said in his autobiographical book "The Art of the Deal," the role thrills him.

"Money was never a big motivation for me, except as a way to keep score. The real excitement is playing the game," he wrote.

The difference now is that he's playing with drones, warplanes, cruise missiles and other lethal cards in a game that risks plunging the United States into yet another Middle Eastern war.

With last Friday's stunning drone strike against key Iranian general Qasem Soleimani, outside the airport in the Iraqi capital Baghdad, Trump yet again upended the status quo -- and alarmed his critics.

The attack was "wildly counterproductive," said John Mueller, a foreign policy expert at Ohio State University.

Soleimani has been a top US enemy during two decades of conflict in the region.

But Trump's predecessors, Barack Obama and George W. Bush, are said to have held off from killing the wily commander of Iran's Revolutionary Guard Corps for fear of the consequences.

As pointman for Tehran's wide-ranging regional network of official and covert military alliances, Soleimani was far more than just a general -- he was one of the most important figures in Iran.

His killing, Mueller said, "will unify people on the side of the mullahs" just when their theocratic, deeply anti-US regime is increasingly unpopular.

Trump, as usual, pronounced himself free of such concerns.

"He should have been taken out many years ago!" the president tweeted soon after the killing.

"General Qassem Soleimani has killed or badly wounded thousands of Americans over an extended period of time, and was plotting to kill many more... but got caught!"

- Reckless or refreshing? -

Trump justified his trade war with China in much the same way. For decades, other presidents were too weak to dare to take on Beijing's unfair trade practices, he claimed.

With nuclear-armed North Korea, another long-running US foreign policy headache, Trump again threw out precedent.

After first threatening "fire and fury" against the isolated dictatorship, he went on to declare leader Kim Jong Un a good friend, betting that his own charisma and personal touch would succeed where harsher policies had failed.

The results in both cases are mixed.

A thaw has been declared in the trade war, but China remains far from reforming its economy, while the outwardly more friendly North Korea has steadily consolidated its nuclear power status.

Now the Iran drama sees that Trump doctrine being applied for the first time to a crisis with the real risk of imminent war.

And Trump's detractors are nervous that he has blundered, or will blunder, into disaster.

"The moment we all feared is likely upon us," Democratic Senator Chris Murphy tweeted at the weekend.

"An unstable President in way over his head, panicking, with all his experienced advisers having quit, and only the sycophantic amateurs remaining. Assassinating foreign leaders, announcing plans to bomb civilians. A nightmare."

The top Democrat in Congress, Nancy Pelosi, has announced plans to vote on a war powers resolution aimed at putting a check on Trump's military actions to avert a "serious escalation" with Iran.

The president's backers, however, say his blunt style and risk-taking policies are exactly what the United States needs.

"This was long overdue," said Thomas Spoehr, a retired army lieutenant general who heads defense studies at the Heritage Foundation think tank.

Following recent attacks against US troops in Iraq and the embassy in Baghdad, Trump had to strike back hard or end up ruining US credibility, Spoehr argued.

"America's reputation, its respect in places like the Middle East, depends on our ability to stand up," he said. "When people cross American red lines..., they know there's going to be a response."

Spoehr pointed to Trump's moving of the US embassy in Israel from Tel Aviv to Jerusalem -- a gesture seen by much of the world as highly provocative to the Palestinians -- as more proof the president has the right instincts.

Predictions that the switch would "set the region on fire" proved far-fetched, Spoehr said.

Trump "doesn't constrain himself with normal conventional wisdom."