(Bloomberg) -- The United Nations has turned into another battleground over the military coup in Myanmar, with the country’s anti-junta ambassador in New York refusing to give up his seat and the military’s actions coming under Security Council scrutiny.

The continuing crisis in the Southeast Asian nation -- Wednesday was the deadliest day of protests with 38 people killed -- will be the focus of a closed-door Security Council meeting on Friday. It’s an early leadership test for U.S. Ambassador Linda Thomas-Greenfield, who was confirmed to her post last week and holds the rotating presidency of the Security Council for March.

The military junta in Myanmar announced it replaced Ambassador Kyaw Moe Tun after he made a dramatic speech at the UN General Assembly last week in defense of the demonstrators while holding up the three-finger “Hunger Games” salute adopted by activists throughout the country.

But the ambassador says he’s still the envoy, and he won support from Thomas-Greenfield, who met with him this week and commended his “courageous and compassionate statement.” In the latest twist, the deputy ambassador the junta installed in his place quit his post after facing criticism.

The deputy’s decision to resign was confirmed by a letter from the Myanmar mission to UN Secretary-General Antonio Guterres on Wednesday seen by Bloomberg News.

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“I am the one who has received a good public servant badge, who has served for more than three decades,” Tin Maung Naing, the departing deputy UN ambassador, wrote on Facebook. “I am the one who is loyal to the state. Due to this situation, I had to decide to leave my job, which I love and value very much.”

Western powers are expected to try to ratchet up pressure on the junta at the Security Council meeting Friday. Yet diplomats and experts say it will be hard to win support from Russia and China for sanctions against the military leaders.

“There will inevitably be calls for UN sanctions, but I don’t think China and Russia are ready to go that far, and the military have already declared that they are willing to absorb any sanctions anyway,” said Richard Gowan, UN director for the International Crisis Group. Western powers want to “nudge the Chinese to use their influence to resolve the situation, or at least send a signal to the junta to ratchet down violence.”

That effort follows China’s decision last month, which surprised many diplomats, to support a statement stressing the need to uphold democratic institutions, even as it stopped short of calling the Feb. 1 takeover a coup.

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Ahead of Friday’s meeting, the UN’s special rapporteur on human rights in Myanmar, Thomas Andrews, issued a report detailing the forced displacement of thousands of people and decrying the junta’s “unrelenting brutality.” He urged nations to “deny recognition of the military junta as the legitimate government representing the people of Myanmar precisely because they are not.”

In his speech to the General Assembly last week, Myanmar’s UN envoy also appealed to the international community “to use any means necessary to take action against the Myanmar military” while calling on the military “to immediately relinquish power and release those detained.”

But the junta has shown it’s not likely to buckle under international pressure. UN Special Envoy for Myanmar Christine Schraner Burgener told reporters on Wednesday that after she warned junta leaders that the Security Council might take strong measures they replied that they are “used to sanctions and ‘we survived the sanctions time in the past.’”

“I also warned they will go in an isolation,” she added, saying they replied that “we have to learn to walk with only few friends.”

It’s not clear if the junta will seek to install a different ambassador to the UN. If it does, the dispute over the leadership could head to the UN’s credentials committee, which reviews disputes over representation.

“Let’s be honest here,” Stephane Dujarric, the spokesman for Secretary-General Guterres, told reporters this week. “We’re in a very unique situation we have not seen in a long time.”

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