WASHINGTON — The president of the United States lands with all the majesty of Air Force One, waiting to exit the front door and stride down the rolling staircase to the red-carpeted tarmac. Except that there is no rolling staircase. He is forced to exit — as one China expert put it rather undiplomatically — through “the a**” of the plane.

This happened Saturday at Hangzhou airport. Yes, in China. If the Chinese didn’t invent diplomatic protocol, they surely are its most venerable and experienced practitioners. They’ve been at it for 4,000 years. They are the masters of every tributary gesture, every nuance of hierarchical ritual. In a land so exquisitely sensitive to protocol, rolling staircases don’t just disappear at arrival ceremonies. Indeed, not one of the other G-20 world leaders was left stranded on his plane upon arrival.

Did President Xi Jinping directly order airport personnel and diplomatic functionaries to deny Barack Obama a proper welcome? Who knows? But the message, whether intentional or not, wasn’t very subtle. The authorities expressed no regret, no remorse and certainly no apology. On the contrary, they scolded the press for even reporting the snub.

No surprise. China’s ostentatious rudeness was perfectly reflective of the world’s general disdain for President Obama. His high-minded lectures about global norms and demands that others live up to their “international obligations” are no longer amusing. They’re irritating.

Foreign leaders have reciprocated by taking this administration down a notch knowing they pay no price. In May 2013, Vladimir Putin reportedly kept the U.S. secretary of state cooling his heels for three hours outside his office before deigning to receive him. Even as Obama was hailing the nuclear deal with Iran as a great breakthrough, the ayatollah vowed “no change” in his policy, which remained diametrically opposed to “U.S. arrogant system.” The mullahs followed by openly conducting illegal ballistic missile tests — calculating, correctly, that Obama would do nothing. And when Iran took prisoner 10 American sailors in the Persian Gulf, made them kneel and broadcast the video, what was the U.S. response? Upon their release, John Kerry publicly thanked Iran for its good conduct.

Why should Xi treat Obama with any greater deference? Beijing illegally expands into the South China Sea, meeting only the most perfunctory pushback from the US. Obama told CNN that he warned Xi to desist or “there will be consequences.” Is there a threat less credible?

Putin annexes Crimea and Obama crows about the isolation he has imposed on Russia. Look around. Moscow has become Grand Central Station for Middle East leaders seeking outside help in their various conflicts. As for Ukraine, both the French president and the German chancellor have hastened to Moscow to plead with Putin to make peace. Some isolation.

Iran regularly harasses our vessels in the Persian Gulf. Russian fighters buzzed a U.S. destroyer in the Baltic Sea. And just Wednesday, a Russian fighter flew within 10 feet of an American military jet. The price they paid? Being admonished that such provocations are unsafe and unprofessional. An OSHA citation is more ominous.

Add to that American acquiescence not just to ransoming hostages held by Iran, but to delivering the loot by unmarked plane filled with stacks of cold (untraceable) cash, like a desert drug deal. Why the stealth? Obviously to conceal the manner of the transaction from Congress and the American public. Some humiliations are so grotesque that even the Obama team can’t miss it.

Now the latest. At the G-20, Obama said he spoke to Putin about cyberwarfare, amid revelations that Russian hackers have been interfering in our political campaigns. We are more technologically advanced, both offensively and defensively, in this arena than any of our adversaries, said Obama, but we really don’t want another Cold War-style arms race.

Instead, we must all adhere to norms of international behavior.

It makes you want to weep. This KGB thug adhering to norms? He invades Ukraine, annexes Crimea, bombs hospitals in Aleppo — and we expect him to observe cyber-code etiquette? Rather than exploit our technological lead — with countermeasures and deterrent threats — to ensure our own cyber safety?

We’re back to 1929 when Secretary of State Henry Stimson shut down a U.S. code-breaking operation after it gave him decoded Japanese telegrams. He famously explained that “gentlemen do not read each other’s mail.”

Well, comrade, Putin is no gentleman. And he’s reading our mail.

Charles Krauthammer’s email address is letters@charleskrauthammer.com.

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