U.N. Secretary-General Antonio Guterres attends a news conference in Istanbul, Turkey, February 10, 2017.

© 2017 Reuters

Halfway through his first five-year term, U.N. Secretary General António Guterres is becoming defined by his silence on human rights — even as serious rights abuses proliferate.

U.N. secretaries general have all struggled with when to speak out, trying to balance their role as quiet mediators of disputes with the need to represent core U.N. values. Outspoken support for rights can close some diplomatic doors but keeping quiet leaves the perception that the United Nations is indifferent to atrocities, abandoning the victims while often undermining prospects for peace. Guterres has firmly sided with quiet diplomacy.

He set the tone early in his tenure, which corresponded with President Trump’s inauguration. Guterres criticized Trump’s “Muslim ban” only after many other governments had condemned it — and then without mentioning Trump.

Guterres perhaps didn’t want to risk giving Trump an excuse to stop sending checks to the United Nations. But that reluctance to speak out has also characterized his approach to other powerful governments such as Saudi Arabia, China and Russia.

Numerous governments have voiced concerns about China’s detention of 1 million Turkic, mainly Uighur, Muslims for forced indoctrination. Yet Guterres has not said a word about it in public. Instead, he praises China’s development prowess and rolls out the red carpet for President Xi Jinping.

Guterres has also repeatedly declined to exercise his authority to establish fact-finding missions into egregious rights violations, such as Saudi Arabia’s murder of Post contributing columnist Jamal Khashoggi, the use of chemical weapons in Syria, and the murder of two U.N. sanctions monitors in Congo.

Apart from his spokesman’s feeble appeal to the United States to fulfill its legal obligations as host for the United Nations, Guterres has stayed silent on the Trump administration’s revocation of a visa for the International Criminal Court’s chief prosecutor over possible investigations of U.S. torture in Afghanistan. By contrast, Guterres needlessly allowed himself to be photographed at a recent African Union summit standing next to then-Sudanese President Omar Hassan al-Bashir, who is wanted by the International Criminal Court on charges of war crimes, crimes against humanity and genocide in Darfur.

On rare occasions, Guterres has taken a principled stand for rights, including resisting Guatemalan President Jimmy Morales’s campaign to destroy the U.N.-backed International Commission Against Impunity in Guatemala as it investigates Morales for corruption. In September 2017, Guterres urged the Security Council to stop the Myanmar military’s ethnic cleansing of Rohingya Muslims, albeit with little follow-up when it did nothing.

But for most rights issues, the dominant sound coming from the 38th floor of U.N. headquarters has been silence.

There is no doubt that Guterres is a skilled and conscientious diplomat, but his decision to suppress his voice on human rights, especially as civilians are targeted in armed conflicts, is misguided.

The Syrian military, with the support of Russia, Iran and Hezbollah, has systematically attacked civilians and civilian institutions such as hospitals in areas held by anti-government forces. The Saudi-led coalition has repeatedly attacked markets, mosques, funerals and even a school bus in Yemen while maintaining a blockade that has exacerbated the world’s largest humanitarian crisis, with millions facing famine. The Myanmar military committed widespread and systematic murder, rape and arson to force more than 730,000 Rohingya Muslims to flee to Bangladesh. To pretend that these conflicts can be mediated without addressing the human rights abuses at their core is to divorce the negotiating room from the ugly reality on the ground.

Peace talks for Syria have been on and off again for years. But if Guterres remains silent about the government’s responsibility for the vast majority of atrocities that are at the heart of the conflict, it will only make peace more elusive.

The rise of autocrats presents a profound threat to human rights, yet Guterres is also notably silent, even without a mediating role to play.

Other U.N. chiefs have managed a better balance. Kofi Annan’s human rights voice arguably enhanced his power as a mediator. Ban Ki-moon launched “Human Rights up Front,” to ensure that U.N. field representatives did not prioritize good relations with a government over speaking out against atrocities they witnessed. Under Guterres, that important initiative has been sidelined.

For more than two years, Guterres offered excuses for not publicly defending human rights. He wanted to focus on internal reforms. He needed to stabilize relations with Trump. But today’s crises are too acute, the civilian victims too numerous, for Guterres to reduce his job to mediator in chief.

Speaking out is never easy. There is often a political, even a personal, price to pay. But that is the cost of leadership. Guterres should show that he can fulfill the full scope of his responsibilities as U.N. secretary general. His excessively quiet diplomacy is selling short his position and the promise of the United Nations.