Amina Mohammed, a Nigerian politician and diplomat, has been the deputy secretary-general of the United Nations since 2017. Earlier this month she committed a gaffe: She inadvertently told the truth.

At a press conference, Mohammed was asked by Jimmy Quinn of National Review about the organization’s blatant policy of discriminating against residents of Taiwan. For years, any visitor presenting a Taiwanese passport has been barred from entering UN premises anywhere in the world. Quinn inquired: Doesn’t this exclusion of individuals from Taiwan hold back the UN’s efforts to achieve its top declared goals, namely peace, prosperity, progress, and sustainability?

“I think exclusion of anyone holds back the goals,” Mohammed promptly and sensibly replied. “We said leave no one behind, and I think member states have to find a way to make sure that we are not in the position where we’re excluding people. Every person matters, whether from Taiwan or otherwise, and I think it’s really important for member states to find a solution to that.”

Hardly had the world body’s second-highest official uttered those decent words, however, than the UN bureaucracy rushed to suppress them. When spokesperson Farhan Haq was asked point-blank how, in light of the deputy secretary general’s words, the UN could justify “excluding Taiwanese by not letting them into UN headquarters,” his tangled, stammered response was to pretend that he had been asked about China. He wouldn’t even utter Taiwan’s name.

“We — we don’t intend to leave any of the people of China behind, and we support all of the people of China, but — but — but we stick by the one-China policy as — as has been decided by the General Assembly,” he spluttered.

Except that the General Assembly never decided that Taiwan’s 24 million citizens must be regarded as nonpersons. The “one-China policy” dates back to the 1971 resolution that China would henceforth be represented in the United Nations by the Communist government in Beijing, replacing the Taiwanese government in Taipei. Since then, Taiwan has evolved into a modern, liberal democracy, actively engaged in commerce with the world. Its people overwhelmingly consider their nationality Taiwanese, not Chinese. Yet China has the audacity to claim that Taiwan is not a true country but merely a renegade Chinese province. It’s a wholly preposterous claim, not least because the Chinese Communist Party has never governed Taiwan.

Nevertheless, UN officials go along with Beijing’s claim. They deny Taiwan, one of Asia’s freest and most advanced nations, a seat on global forums. Even worse, UN personnel treat individual Taiwan citizens as pariahs. Holders of an ordinary Taiwan passport can travel, visa-free, to 145 countries, including the United States, Japan, Israel, and most of Europe. But if they show up at the UN and offer their Taiwan passport as identification, the door is shut in their face.

I spoke last week with Lennon Chang, a Taiwanese professor of criminology at Australia’s Monash University. He described what it’s like to be snubbed in this manner. On one occasion, arriving for a meeting of scholars at the UN Conference Center in Bangkok, he presented his Taiwan passport and was denied entry. Only when he produced an ID that didn’t mention his country’s name was he permitted to join his colleagues.

On another occasion, Chang collaborated with a UN agency on a project underwritten in part by the Australian government. Impressed with his skill, agency officials proposed that he work with them on a follow-up project. But once they learned that he was Taiwanese — the matter hadn’t previously come up — they abruptly pulled the plug.

Such biased treatment is routinely meted out to Taiwanese reporters, students, and tourists, who are guilty only of being citizens of a country that the world’s most powerful dictatorship claims for itself. It is as if Moscow were to insist that Ukraine is Russian and that Ukrainians must be barred from every UN forum and facility.

It bears repeating: No UN resolution requires Taiwan’s exclusion. The very notion is absurd: The UN was created, according to the opening sentence of its charter, to uphold “the dignity and worth of the human person [and] the equal rights … of nations large and small.” China’s outrageous demand that Taiwan be treated as an international leper shouldn’t be indulged. It should be repudiated forcefully.

More than once, Beijing has threatened to go to war to conquer Taiwan. The last thing America and its allies ought to be doing is trying to appease such a menacing bully. Every time China is allowed to muscle the UN into humiliating its small neighbor, war becomes just that much more likely. The blackballing of democratic Taiwan is both wrong and dangerous. Why does the free world tolerate it?