Adm. Harry Harris, the top US military official overseeing operations across Asia who had been tapped as ambassador to Australia, is likely to be named instead as US ambassador to South Korea, according to two sources with knowledge of the matter.
Moving Harris, who currently serves as commander of US Pacific Command, was Secretary of State nominee Mike Pompeo's idea, ahead of potential talks between President Donald Trump and North Korea's leader Kim Jong Un, the sources said.
One source told CNN that Pompeo has proposed the switch pending Trump's blessing.
Harris' confirmation hearing to be ambassador to Australia was scheduled for Tuesday but was postponed.
"At the request of the administration, the hearing has been postponed until early May," said Micah Johnson, a spokeswoman for Senate Foreign Relations Chairman Bob Corker.
While Seoul is arguably the most important diplomatic post with potential Kim talks looming, Australia is also a "Five Eyes" intelligence-sharing partner that would need a new ambassador to go through the confirmation process if Harris shifts.
Australian Foreign Minister Julie Bishop told CNN-affiliate Sky News on Wednesday that acting Secretary of State John Sullivan had informed her of the change.
She played down any suggestion the decision to switch Harris's posting was a slight against Australia. "This is not unusual, it has happened before but we look forward to a new ambassador being nominated as soon as possible," she said.
However, Andrew Shearer, senior adviser on Asia-Pacific Security at the Center for Strategic and International Studies, said it was hard to avoid the impression Australia was being treated as a "second-class ally."
"(Australia) is a victim of the Trump administration's shambolic personnel practices," said Shearer, the former national security adviser to Australian Prime Ministers John Howard and Tony Abbott.
"There's no doubt that there will be intense disappointment in Australia, where Admiral Harris is well known and highly regarded. His nomination had strong bipartisan support and he would have been an effective advocate at a time when the US alliance is a topic of increasing debate because of China's rise and its economic importance to Australia," Shearer said.
The White House did not immediately respond to CNN's request for comment.
The Washington Post first reported plans to move Harris to South Korea.
During his tenure at Pacific Command, Harris has not minced words about North Korea's ambitions.
US forces in the Pacific "must be prepared to fight tonight, so I take him at his word," he said last year about Kim's intentions. "I must assume his claims are true -- I know his aspirations certainly are."
Harris has also watched as an increasingly assertive China has pursued a more muscular military posture in the Pacific and established a military presence on man-made islands in areas the US and its allies contend are international waters.
A 1978 graduate of the US Naval Academy, Harris was designated a naval flight officer after graduation and has held several other command assignments in the Navy, including with the US Pacific Fleet and the 6th Fleet.
Sen. Robert Menendez, the top Democrat on the Senate Foreign Relations Committee, said on Tuesday that he had not been told about plans to shift Harris to South Korea.
"Having a nominee for South Korea I think is incredibly important, and I'd have to hear the admiral's views about the whole challenge of the Korean Peninsula and denuclearization," Menendez said.
The New Jersey Democrat added that having an ambassador to South Korea was important, but that "Australia is important, too, as a Pacific ally."
In January, the Trump administration decided not to nominate Victor Cha -- a long rumored candidate to be US ambassador to South Korea -- a reversal, sources told CNN at the time, that was driven by a disagreement over a "bloody nose" strike against Pyongyang.
Cha, a widely respected academic and former Bush administration official, said in a Washington Post op-ed earlier this year that the answer to the "real and unprecedented threats" North Korea presents is not, "as some Trump administration officials have suggested, a preventive military strike."
Instead, Cha laid out what he called "a forceful military option available that can address the threat without escalating into a war that would likely kill tens, if not hundreds, of thousands of Americans."
South Korea is just one of dozens important ambassadorships that remain vacant.