An aging North Korean nuclear strategist involved in now-dormant disarmament deals. His former interpreter in international negotiations who is now North Korea's highest-ranking female diplomat.

Kim Kye Gwan and Choe Son Hui are among the best-known North Korean officials after leader Kim Jong Un and his family members. They are in the news again now after their recent back-to-back comments about the United States were blamed for President Donald Trump's abrupt cancellation on Thursday of a much-anticipated summit with Kim Jong Un. On Friday, Trump said the two sides were working to put the meeting back on track.

A look at who the officials are and how their comments led Trump to spike the summit planned for June 12 in Singapore:

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KIM KYE GWAN

First Vice Foreign Minister Kim Kye Gwan, 75, led the North Korean delegation at much of the off-and-on six-nation nuclear disarmament talks held in Beijing in 2003-2008.

In the talks among the two Koreas, the United States, China, Russia and Japan, he was known for seeking a series of concessions in return for slow disarmament steps. South Korean media called his strategy "salami tactics," comparing it to cutting thin slices off a salami.

Under the agreements reached in the negotiations, North Korea halted atomic activities and disabled key elements of its weapons program in return for security guarantees, shipments of fuel and other aid. But the deals eventually collapsed amid disputes over how to verify the North's disarmament steps. Criticism subsequently flared in Washington, Seoul and elsewhere that the deals only benefited North Korea.

In recent months, Kim Kye Gwan, who was also a senior member of the ruling Workers' Party and a delegate to the rubber-stamp parliament, has been rarely mentioned in state media, triggering speculation that he might be ill.

On May 16, however, he issued a statement threatening to scuttle the Kim-Trump summit to protest what he called Washington's push for one-sided disarmament. That tossed fuel on skepticism in the U.S. about whether North Korea truly intends to deal away its nuclear program.

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CHOE SON HUI

Also a vice foreign minister, Choe, about 54, is one of the few women who hold high-level posts in North Korea's male-dominated ruling elite. Other high-profile women include Kim Jong Un's sister, Kim Yo Jong, who is in charge of the North's propaganda affairs, and his young, popular wife, Ri Sol Ju.

Reportedly a stepdaughter of former Premier Choe Yong Rim, Choe Son Hui worked as an English-language interpreter for Kim Kye Gwan during the six-party talks after studying in Austria and China. She then headed the North American Affairs Bureau at the Foreign Ministry before a state media dispatch in March confirmed her promotion to vice foreign minister.

Seoul's Unification Ministry says Choe is the highest-ranking woman in North Korea's Foreign Ministry.

On Thursday, she grabbed international headlines by calling U.S. Vice President Mike Pence a "political dummy" and threatening to scrap the Kim-Trump summit. "Whether the U.S. will meet us at a meeting room or encounter us at nuclear-to-nuclear showdown is entirely dependent upon the decision and behavior of the United States," she said.

This directly led Trump to say it was "inappropriate" to go ahead with the summit because of the "tremendous anger and open hostility" displayed in the North's "most recent statement."

Kim Kye Gwan tried quickly to calm the situation, saying in a statement that North Korea is still willing to hold talks with the United States "at any time, in any format."