Iran warns it will destroy Israel and start World War III if Donald Trump tears up the nuclear deal. China calls him “as ignorant as a child” and threatens to end all cooperation if Trump doesn’t recognize Taiwan as part of China.

Then there are the Hillary Clinton Democrats, who are trying to steal the election they lost. Some fellow Republicans also are breaking with the president-elect over Russian hacking allegations and his selection of oilman Rex Tillerson for secretary of state.

If you blinked, you missed the Trump honeymoon. He hasn’t taken office, yet already, the long knives are out for him.

The conflicts could be Trump’s baptism by fire, except he ran an endless gauntlet of fire during the 18-month campaign. Numerous reports of his demise were not premature, they were flat-out wrong.

I suspect something similar is happening now. The whole world looks to be having a nervous breakdown over his early actions, and many Americans are wondering if the wheels are about to come off the Trump train. Some on the left, including those in the White House, certainly hope so and are doing all they can to delegitimize his victory and undermine democracy. If only they treated America’s enemies so ruthlessly.

Still, the good news is that they hope and scheme in vain. Trump shows no signs of going wobbly, and while he doesn’t always keep calm, he does carry on.

He has taken the most vicious pounding of any candidate in modern times, and still pulled off one of the great upsets in political history. Why would he buckle now?

As the late Mayor Ed Koch once said of himself: I give ulcers, I don’t get them. So it is with Trump. He takes pleasure in driving his opponents crazy.

If he were the appeasing sort, he would back off now, say soothing things to make the hysterics feel better, and pledge to play nice.

Fortunately, that’s not the man America elected. Trump is a master negotiator, and now that he has the attention of China, Iran and Democrats, he will try to use that as leverage to cut better deals for national security and working Americans.

But Trump is also a pure disrupter, the greatest threat to politics-as-usual ever to win the Oval Office. He may want to negotiate, or he may keep plowing ahead until he gets all that he wants.

The other party never knows which side of him they’re getting. Is he looking to make a deal, or does he want it all?

His life story shows examples of both. The title of his first book is “The Art of the Deal,” but one of the most striking statements in it is this: “My style of deal-making is quite simple and straightforward. I aim very high, and then I just keep pushing and pushing and pushing to get what I’m after.”

That was in 1987. His job has changed, but he’s still pushing to get what he’s after.

That’s why he won the election. Most of the voters in 30 states wanted change, and he was the clear change agent. But change of the magnitude they want and he seeks — wholesale change, at home and abroad — can’t happen smoothly. Many eggs must be broken to rearrange the power structure.

The architects of the status quo, including the mainstream media, establishment leaders of both parties, as well as hostile powers such as China and Iran, have everything to lose from Trump’s agenda. Most of his changes will come at their expense, so they can be expected to fight him all the way, as they are now.

That’s fine, that’s how the Founders devised the separation of powers, and that’s the way the world works — everybody pursues their own interests.

Trump will not always prevail, or always be right. His election was an urgent course correction, but sometimes, the correction will need to be corrected. The key is for him to keep his bond with the American people by speaking directly to them, and listening to what they say in return.

Remember, too, we are in the early stages of the battle for America’s renewal. Whatever you do, don’t be a spectator. And always be prepared to be surprised.

Trashy, trysted tale

That was quite a story in The Post about the sanitation man who drove his city garbage truck to a hot-sheet motel in Brooklyn for a middle-of-the-day “meeting.”

The really sexy element was Neil Puglia’s salary — $78,886 a year, plus benefits.

Times hires ‘tool’ of trade

There’s shock in some media circles that the New York Times hired Glenn Thrush, the Politico reporter who was exposed by WikiLeaks for sending one of his stories pre-publication to Clinton campaign chief John Podesta. “Because I have become a hack I will send u the whole section that pertains to u,” Thrush wrote to Podesta. “Please don’t share or tell anyone I did this.”

I’m not shocked. The Times saw a man it could count on to adhere to the paper’s bias and echo the Democratic Party line, and grabbed him.

You can’t let a hack like that get away.

Blasio is lyin’ king

The criminal probes into whether Mayor Bill de Blasio created an illegal pay-to-play culture at City Hall tend to obscure other distressing features of his tenure. To wit, his stunning incompetence and dishonesty.

Both are evident in his handling of homelessness, and a similar pattern is being revealed on child welfare with the resignation of Gladys Carrion , the beleaguered head of the Administration for Children’s Services. With deaths mounting of children who were known to social workers, Carrion, who broke into tears during City Council testimony six weeks ago, said she was quitting “for my well-being.”

Her exit, part of a parade of top aides out the door, follows “reforms” that saw de Blasio plow money into the agency and add help for troubled homes instead of removing the children for safety.

But, as with the soaring homeless population and everything else except pure politics, the mayor pays little attention until headlines force him to. Then he adopts a posture of misleading defiance for as long as possible before promising more reforms, only to see the problems continue to get worse.

He tried that approach again Tuesday, telling reporters he planned to hire an independent monitor along with Carrion’s replacement.

“We have to think systemically,” he said. “We have to think about what’s going to make this agency stronger given the many, many challenges it faces.”

What he didn’t say, and what became clear hours later, was that Albany had already forced him to hire a monitor, and that the mayor had secretly accepted the order. But instead of admitting the truth, de Blasio tried to make it sound as if it was his idea.

What a putz.