Within hours of the assassination of the Russian ambassador to Turkey, the attack on a Christmas market in Berlin and a shooting in a Zurich mosque, Donald Trump had already come to his own conclusions.

"Today there were terror attacks in Turkey, Switzerland and Germany – and it is only getting worse," the president-elect declared on Twitter. "The civilized world must change thinking!"

When it comes to the Middle East, that tweet was a typical example of what has many Western analysts so worried about Mr. Trump's approach to the region. It was impulsive, ambiguous, ill-informed – and wrong. Swiss police say there was no terrorist connection in the mosque shooting.

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It was also predictable. Mr. Trump's tweets and statements, coupled with his choices for cabinet and senior advisers, suggest to some an approach to the Middle East based on convictions unsupported by experience or facts.

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"This is a radical administration by any definition," warns Daniel Serwer, who heads the Conflict Management Program at the Johns Hopkins School of Advanced International Studies in Washington, D.C., and is a scholar at the Middle East Institute, a think tank. Mr. Trump, he fears, "might well end up in a massive conflagration caused by his intemperate and ill-considered remarks."

Others disagree. Dov Zakheim was an undersecretary of defence in the first administration of George W. Bush, and one of the most prominent names on the open letter signed by more than 50 conservative foreign-policy experts last March declaring Mr. Trump unfit to be president. But he has come around.

"I think there's a growing recognition in the region that our policies may not change all that much," he believes. "… We're clearly seeing the difference between the rhetoric of the campaign and what's going on now and what's likely to go on." He detects a general toning-down of Mr. Trump's language on the Middle East since he became president-elect.

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The contradictions among foreign-policy experts reflect uncertainly surrounding Mr. Trump, his rhetoric and his real intentions for the Middle East as the world braces for his swearing-in. The most acute test may come early, as the new administration grapples with the internal contradictions of its approach to Iran and that country's growing influence throughout the region.

The Middle East is the graveyard of presidential ambition. Lebanon and Iran served Ronald Reagan a diet of grief; the failure of Bill Clinton's efforts to reconcile Israelis and Palestinians helped bring on the second intifada; George W. Bush's presidency was destroyed by his invasion of Iraq; Barack Obama sought to pivot away from the region but was dragged back by the Arab Spring, with disastrous consequences in Libya and Syria.

All of these presidents brought, at the least, goodwill to the question of how to bring peace to the Middle East. Mr. Trump, in contrast, brings an ingrained suspicion of Islam, which he and some of his advisers consider, not a religious faith, but a threatening ideology.

"The disturbing part for many of us in the foreign-policy community … is the extent to which he's holding onto this narrative of us versus them, and them is not terrorism, it's Islam," says Leslie Vinjamuri, a professor of political science at University of London and a fellow at Chatham House, the think tank on international affairs, "and there's this deep fear that it could antagonize many good people that we should be working with."

But Mr. Zakheim is more sanguine. "A lot of the fire and brimstone about Muslims during the campaign was just that – during the campaign," he said. Even during those months, Mr. Trump went from wanting to ban all Muslims from entering the United States to a more ambiguous process of bans or "extreme vetting" for those trying to enter the United States from unsafe countries.

Wednesday, he told reporters at his Mar-a-Lago Florida estate that the attacks vindicated his harsh policies toward Muslim immigration. "You've known my plans all along and I've been proven to be right, 100-per-cent correct," he said. "What's happening is disgraceful."

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Prof. Vinjamuri is also concerned by the paucity of experience in government that characterizes the administration. First and foremost, there is the president-elect, who has never held elected office. As the CEO of ExxonMobil, incoming secretary of state Rex Tillerson knows the region, but from a business rather than a government perspective. Retired General Michael Flynn, Mr. Trump's pick for national security adviser, was director of intelligence for U.S. Central Command, which is responsible for military operations in the Middle East, but could reinforce Mr. Trump's Islamophobia. As recently as last February, he tweeted: "Fear of Muslims is RATIONAL: please forward this to others: the truth fears no questions ..."

Mr. Trump's pick for ambassador to Israel, David Friedman, is a bankruptcy lawyer who has equated liberal Jews with Nazi collaborators, is skeptical of a two-state solution involving Israelis and Palestinians, and shares Mr. Trump's determination to move the U.S. embassy from Tel Aviv to Jerusalem, which could infuriate Palestinians and other Arabs.

On the other side, Mr. Trump's pick for defence secretary, retired General Jim Mattis, is generally respected, despite or because of (depending on your perspective) his obsession over Iran, which he calls "the single most enduring threat to stability and peace" in the Middle East.

It all adds up to a conflicting, contradictory, ad hoc approach to Middle Eastern issues that could quickly lead the administration into fresh quagmires, some fear.

For example, Mr. Trump, in seeking a rapprochement with Russian leader Vladimir Putin, might be willing to recognize Russia's claim over Crimea, which Prof. Serwer fears could lead to cascading claims by ethnic nationalists, ending with Kurdish demands for an independent state carved out of existing states, "where it could become very complicated."

"Because of its singular volatility, the Middle East tends to require policy improvisation more than other regions," observes Jonathan Stevenson, a senior fellow at the London-based International Institute for Strategic Studies. "But before this factor even comes into play, Trump would have to come up with a coherent policy on which to improvise. This he has not yet done."

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Others are more hopeful. Steven Spiegel, director for the Center for Middle East Development at University of California at Los Angeles, finds so many contradictions in Mr. Trump's statements and so many conflicting views within his cabinet choices "that what we can predict is controversy, and what happens when you have so much controversy is that you tend to go to the middle, and when you go to the middle, the policy tends to look more conventional."

Mr. Trump's approach to Iran is at the heart of these conflicting prophesies. The incoming president is likely to support, or at least tolerate, even greater Russian intervention in the Syrian civil war on behalf of the Alawite regime led by Bashar al-Assad.

But Iran also supports the Syrian strongman, and with each victory by the regime, Tehran's influence grows. Yet Mr. Trump is strongly anti-Iranian. He has called the agreement negotiated by the Obama administration and Tehran to put its nuclear weapons program on hold "disastrous," and vowed to rip it up, which would alarm allies who value the respite, even if it is temporary, from the prospect of a nuclear-armed Iran.

One approach may be to quietly abandon plans to terminate the nuclear agreement, while moving to contain Iranian influence elsewhere. But would the new administration have the skill and patience to pursue such a strategy? Many analysts are doubtful. But Mr. Zakheim is more optimistic. Mr. Trump's cabinet picks suggest that, "If anything, we're likely going to take a much tougher line on Iran, which will please all the rest of the Arabs in the region," he believes. "If anything, it's continuity-plus."

One of the greatest concerns surrounding Mr. Trump centres on, not his policies, but his personality. Paul Salem is vice-president for policy and research at the Middle East Institute. "He seems to be unpredictable, thin-skinned," he observes. "As he himself says, he's a counterpuncher." But the Middle East is a place where a counterpunching American president can foment disaster.

And then there is the greatest fear of them all: the unexpected. "The Middle East always comes up with a big surprise," Mr. Salem points out. The measure of any president "is how they react to these big surprises."

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"The greatest concern with Donald Trump is over his personality – his impulsiveness, his shooting from the hip, his being emotional," Prof. Vinjamuri states. "There's a strong sense of someone whose ego needs to be very carefully massaged and handled, and if it's not, then what comes back at you could be quite difficult."

But Mr. Zakheim and Prof. Spiegel remain hopeful that there will be enough voices in the room urging caution to restrain Mr. Trump's impulsive tendencies. Mr. Stevenson suspects a few harsh lessons may impose that caution on a chastened president.

"Trump may learn that taking an unsubtle, predominantly muscular line in the Middle East is unsustainable," he suspects. "It's easy to talk tough; being too tough and accepting the consequences is another matter."