Washington (CNN) President Donald Trump's sudden and barely believable spat with Denmark shows how he has turned American diplomacy into a reflection of his tempestuous, erratic personality.

The world's most powerful nation now conducts its business in an unpredictable, often vengeful and transactional way . It's sensitive to slights and susceptible to flattery. Like its author, US statecraft is fixated with pleasing Trump's political base. And it's all delivered in world-shocking tweets that bypass traditional foreign policy processes in a stream of consciousness between Trump's impulsive brain and the rest of the planet.

The result is that the United States, which lifted the Western world out of the rubble of World War II and to victory in the Cold War, is no longer an essential anchor of global stability. America's foreign relations rarely advance careful strategies gamed out exhaustively in the US government or even conform with the Enlightenment values of its founders.

Instead, US foreign policy often looks like an extension of the family business -- made obvious by Trump's son-in-law Jared Kushner's mysterious and expansive role as a de facto secretary of state and Ivanka Trump's appearances at global summits.

He can't get along with the neighbors either. Canada and Mexico have largely been ignored -- or insulted -- by the President. Trump is yet to make a presidential visit to Mexico -- the nation he accused of sending criminals and rapists across the border in his 2016 campaign.

By the equivalent point of his presidency, Barack Obama had been to Mexico and Canada twice. George W. Bush had paid three visits south of the border and two to Canada.

The one time Trump did travel to Canada as President was for a G7 summit that he blew up by feuding with allies. French President Emmanuel Macron, whose early bromance with Trump has cooled, announced Wednesday's that this year's G7 at the weekend would not feature a final communique -- apparently to avoid a new showdown with the US President.

On policy on Iran and Israel, North Korea and Britain's exit from the European Union Trump has often appeared to using diplomacy to further his own political goals, rather than an objective understanding of traditional American interests.

Many traits of Trump era diplomacy are on show in the current estrangement with Denmark.

He effectively canceled a state visit to a NATO ally that has shed blood with the US in the post 9/11 wars, because it balked at his idea to buy a piece of its territory -- Greenland.

And then he felt insulted.

"I thought that the Prime Minister's statement that it was absurd ... was nasty," Trump told reporters Wednesday. "Respect has to be shown to the United States."

The showdown with Copenhagen was also typical of Trump because it is impossible to believe it could have happened under any other presidency and because it ultimately escalated because of his personal pique. But there might have been a political upside -- the spectacle of Trump berating a foreign country, especially a European one, fits nicely into his "America First" routine and may also appeal to his core supporters.

Allies walking on eggshells

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It was never clear whether the President was actually serious about trying to buy Greenland, an autonomous Danish territory, after The Wall Street Journal broke the story

But the fact that the thin-skinned President felt personally insulted by Denmark's response to the idea epitomizes the walking-on-eggshells behavior now required of US allies.

The Denmark debacle is also Trumpian in that his fury detracted from the underlying seriousness of the issues he was raising. Often, the President has a knack for tackling taboos about America's global posture and the international system that a more traditional commander-in-chief might have avoided.

Greenland does raise important strategic questions that the US must answer. Climate change's impact on melting ice is making oil, gas and mineral deposits more accessible. And the Arctic is seeing a new geopolitical great game among the US, Russia and China.

Similarly, many in Washington agree with Trump that China needs to be confronted over intellectual property theft and trade. And International institutions could benefit from reform, though not perhaps the violent shakeup envisaged by Trump's supporters.

But Trump is yet to prove that his undiplomatic diplomacy is likely to address such crucial questions in an effective way, or that he is searching for anything more than a headline.

Trump's kerfuffle with Denmark is not an outlier. It's consistent with how he has treated America's traditional friends. Britain, France, Japan, South Korea, Germany and Sweden have all felt the lash of his tongue and sting of his tweets.

Winners and losers

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Trump's international quarrels may be rooted in his testosterone-fueled view of a world of winners and losers where American strength can be deployed against smaller and weaker states.

He has little time for the concept of alliances in international relations in which America has traditionally multiplied its power and values around the globe. For Trump, allies and their leaders are mostly freeloaders who have exploited America's generosity to get rich at its expense and are only of use if they agree with him.

He also sees America's relations through the prism of his personal relationship with foreign leaders rather than as a culmination of common interests and conflicts.

So he boasts about how he and North Korean tyrant Kim Jong Un "fell in love" or his "incredible relationship" with China's Xi Jinping -- even though it's arguable whether either bond has yet delivered tangible benefits to wider US interests.

And while he courts US adversaries, especially those with dictatorial leaders, Trump snubs friends.

It's notable that while Trump was bullying Denmark on Tuesday, he was relaunching his effort to get a Western foe -- Russian President Vladimir Putin who assaulted US sovereignty by election meddling -- and redrew borders of post-World War II Europe by annexing Crimea, back into the G8 summit.

Denmark's leader was meanwhile left with the now familiar task for allied leaders of quelling domestic uproar caused by Trump in order to preserve relations with the US.

"A discussion has been raised about a potential sale of Greenland -- this has clearly been rejected," Prime Minister Mette Frederiksen said in Copenhagen.

"This does not change the character of our good relations," Frederiksen added.

Other Danish politicians were not so discrete.

"It's an insult from a close friend and ally," Michael Aastrup Jensen, a Danish lawmaker from the center-right Venstre party, told The Washington Post

'Not the way to treat an ally'

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Such discord is unhelpful to US diplomats abroad since it boosts politicians hostile to America. It also makes it more difficult for allied leaders to create the political room they need to cooperate with America's global priorities.

Denmark has paid a disproportionate price in America's recent wars. It lost a combined 50 service members in Afghanistan and Iraq -- a heavy toll in a nation of only 5.7 million people.

Such figures point to potential long term damage of the President's bullying.

Will Denmark's leaders -- in America's next hour of need -- have the political capital to send their troops to fight alongside America's?

"I think it's sad, honestly, because this is just not the way you treat an ally," Rufus Gifford, who served as ambassador to Copenhagen told CNN's "New Day" on Wednesday.

Most presidents act as political animals and while seeking to maximize their leverage carefully study the domestic constraints facing their foreign interlocutors.

Not Trump.

In fact, his interventions have seemed calculated to make life more difficult for former British Prime Minister Theresa May, Macron or German Chancellor Angela Merkel.

His Twitter diplomacy also makes life impossible for his subordinates. He famously tweeted at former Secretary of State Rex Tillerson that he was "wasting his time" talking to North Korea's "Little Rocket Man" -- then did exactly the same thing himself. Trump's sudden announcement of a Syria withdrawal last year prompted the resignation of Defense Secretary James Mattis.

Current Secretary of State Mike Pompeo has dealt better with the President's political whiplash.

But even his patience may have limits.