(Bloomberg) -- The U.S. and China should work together to show “honest leadership” or risk transforming the pandemic into a bigger crisis, the head of the World Health Organization said in unusually stern comments on the two superpowers.

At the height of the Cold War, the U.S. and the Soviet Union still came together to fight and eradicate smallpox, Director-General Tedros Adhanom Ghebreyesus said. He urged all countries, political parties and the media to stop trying to use the coronavirus issue to divide people.

“If you don’t want many more body bags, then you refrain from politicizing it,” Tedros said at a briefing in Geneva Wednesday. “No using Covid-19 to score political points.”

U.S. President Donald Trump said Tuesday that the WHO “blew it” and had given bad advice on travel restrictions. He threatened to cut funding, saying that the Geneva-based organization favors China. That country’s foreign ministry has suggested that the U.S. army might have caused the outbreak.

Tedros said the WHO tries to treat everyone equally, and will later assess successes and failures. The organization officially informed all member states of the outbreak Jan. 5 and gave guidance on how to test for it by Jan. 10.

The WHO declared a global health emergency in late January, when the world outside China had reported 98 cases and yet no fatalities. Hours later, the U.S. told Americans not to travel to China because of the risk of infection, and for weeks, Trump referred to the disease as the “Chinese virus.”

The WHO plans to update its strategy and give an estimate of the financial needs for the next phase in coming days, Tedros said. Financial resources won’t be a problem as long as countries are united, he added.

“When there are cracks at the national level and global level, that’s when the virus succeeds,” Tedros said.

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