SEOUL — When reports emerged late last year that South Korea had agreed to sell artillery shells to help the United States replenish its stockpiles, it insisted that their “end user” should be the U.S. military. But internally, top aides to President Yoon Suk Yeol were worried that their American ally would divert them to Ukraine.
Mr. Yoon’s secretary for foreign affairs, Yi Mun-hui, told his boss, National Security Adviser Kim Sung-han, that the government “was mired in concerns that the U.S. would not be the end user if South Korea were to comply with a U.S. request for ammunition,” according to a batch of secret Pentagon documents leaked through social media.
The secret report was based on signals intelligence, which meant that the United States has been spying on one of its major allies in Asia.
Both Mr. Yi and Mr. Kim stepped down last month for unclear reasons. Neither man could be reached for comment.
Mr. Yoon’s office did not immediately respond to a request for comment.
Although U.S. officials have confirmed that the trove of leaked documents appear to be legitimate intelligence and operational briefs compiled by the Pentagon’s Joint Staff, at least one had been modified from the original at some point. And the apparent authenticity of the documents is not an indication of their accuracy.
The documents pertaining to South Korea showed a key American ally torn between Washington’s pressure on Seoul to help supply ammunition to Ukraine and its official policy of not providing lethal weapons to countries at war. Seoul feared that President Biden would call Mr. Yoon directly to press the matter.
“Yi stressed that South Korea was not prepared to have a call between the heads of state without having a clear position on the issue, adding that South Korea could not violate its policy against supplying lethal aid, so officially changing the policy would be the only option,” the document said.
Mr. Yi said that Mr. Yoon’s presidential secretary for national defense, Im Ki-hun, had promised to determine “a final stance by March 2.”
But their boss, Mr. Kim, was worried that if the announcement of Mr. Yoon’s state visit to Washington coincided with an announcement of South Korea changing its stance on providing lethal aid to Ukraine, “the public would think the two had been done as a trade.” Mr. Yoon’s state visit to Washington, which is to take place on April 26, was announced March 7.
Instead, according to the document, Mr. Kim “suggested the possibility” of selling 330,000 rounds of 155-mm artillery shells to Poland, since “getting the ammunition to Ukraine quickly was the ultimate goal of the United States.”
Mr. Yi agreed that it might be possible for Poland to agree to being called the end user and send the ammunition on to Ukraine, but that South Korea would need to “verify what Poland would do.” It is unclear exactly what he meant by this, since South Korea’s export control rules stipulate that its weapons or weapon parts sold to a foreign country should not be resold or transferred to a third country without Seoul’s approval.
“South Korea’s position has been that it will cooperate with the United States while not clashing with Russia,” said Yang Uk, a weapons expert at the Asan Institute for Policy Studies in Seoul. “The documents leaked put South Korea in a more difficult position.”
And the mere fact of the spying taking place, leaving aside what it might uncover, is a damaging revelation, he said.
“It’s reasonable to suspect that the United States spies on top defense and security officials in Seoul, but it’s bad news for the general public ahead of the South Korea-U.S. summit,” he added. “People will ask, ‘We have been allies for seven decades, and you still spy on us?’”
