What would happen if a president talked to world leaders in the same explosive patter Donald Trump perfected on the campaign trail?

You can get a clue from the off-the-cuff phone talks the president-elect has been holding with foreign leaders since winning the election. These freewheeling calls have veered from insulting to astonishing and raised questions about US policy shifts that Trump seems not to have intended.

Case in point: Trump holds a phone schmooze with the Taiwanese president, apparently unaware that it could cause a crisis with China. Beijing may view the call as a break in a 37-year-old US policy of not recognizing Taiwan, which China regards as a renegade province. This is the most sensitive issue in US-Chinese relations, yet Trump is heedless.

It makes one wonder when someone (and who?) will tell Trump his words and tweets are being taken seriously by foreign leaders — even if not by him.

Think for a moment of the suggestion Trump made by phone to British Prime Minister Theresa May. “If you travel to the US you should let me know,” he carelessly told the leader of America’s closest ally two days after the election. Then Trump went on to hold (in his words) “a very productive meeting” on Nov. 12 at Trump Towers with Nigel Farage, the Brit who led the destructive British campaign to exit the European Union. May opposed Brexit, but as if to compound his insult, Trump openly suggested she appoint Farage as ambassador to Washington, a suggestion London quickly rebuffed.

Did Trump deliberately intend to insult May? Does he want to promote the breakup of the European Union, which is what Farage and Vladimir Putin are seeking? Or was Trump just indulging in chitchat, oblivious to the foreign-policy impact of his words?

Either way, Trump’s careless words have led to counterproductive confusion about what he really means.

Even more startling than his insult to May was the conversation Trump held with Pakistani Prime Minister Nawaz Sharif, who called to congratulate him on his victory.

Keep in mind the United States has deep and dangerous disputes with Pakistan. Despite billions in US aid over many years, the Pakistani military and ISI intelligence service are still supporting the Afghan Taliban along with the Haqqani network. Both groups are currently battling Afghan forces being trained by US advisers.

Trump himself tweeted in 2012 that “Pakistan is not our friend.” Yet in his chat with the Pakistani leader, the president-elect waxes effusive, calling Sharif a “terrific guy” who is “doing amazing work” in a “fantastic country of fantastic people.” Then Trump says he is “ready and willing to play any role you want me to play to address and find solutions to the outstanding problems. I will personally do it.” (There were so many “terrifics” and “amazings” in reports of the conversation that at first I thought it was a parody from the satirical paper the Onion.)

But wait. How do we know what Trump said? We know because Sharif was so delighted with the call that he breached protocol and had the Pakistani Information Ministry release its own readout, which hasn’t been denied by the Trump transition office.

No wonder Afghan and Indian officials are wondering whether Trump is contemplating a new policy of embracing their country. As for the Pakistanis, the initial response, as I was told by the former Pakistani Ambassador to Washington, Husain Haqqani, was “We can carry on as usual, this guy has praised us, he likes us.

“You have to carefully calibrate your message to Pakistan,” adds Haqqani. “This was not calibrated.”

Which raises the question of who, if anyone, will calibrate Trump’s verbiage once he takes the presidential oath.

In principle, the gravitas of the office should have an effect, as should the intelligence and foreign-policy briefings needed to bring an inexperienced president-elect up to snuff. But so far, the president has rebuffed State Department and most intelligence briefings. He clearly prefers to keep schmoozing as if he were still running a business or a TV show.

So far Trump’s advisers haven’t reined him in — and there is little sign they are willing — and his foreign-policy team is still being assembled. But his closest national security adviser, retired Lt. Gen. Michael Flynn, is also a hotheaded personality with a penchant for explosive rhetoric. In my several conversations with people who have worked with Flynn, they concur that he’s unlikely to put the brakes on his boss.

As for Trump’s pick for secretary of defense, retired Gen. James Mattis, if confirmed, will have his hands full with his own job and be in no position to muzzle his boss on rhetoric that might adversely affect US interests. And anyway, Trump has said he knows more than the generals.

Yet Trump’s loose tongue is no joke. Careless talk with Putin — which would no doubt leak — could convince the Russian leader that he can conduct further aggression in the Mideast and Europe. Careless talk with Taiwan’s leader could cause a blowup with China before Trump even decides to start a trade war with Beijing. Etc., etc.

On the other hand, a constant barrage of loose talk may convince foreign friends and foes that Trump is a reality showman whom they do not need to take seriously — not a president who means what he says.

By Trudy Rubin

Trudy Rubin is a columnist and on the editorial board of the Philadelphia Inquirer. -- Ed.

(Tribune Content Agency)