In this pool photograph distributed by the Russian state agency Sputnik, Russian President Vladimir Putin (left) and North Korea's leader Kim Jong Un attend a gala concert in Pyongyang, on Wednesday. Gavriil Grigorov/Pool/AFP via Getty Images hide caption
North Korea's leader Kim Jong Un walks to a meeting with then-President Donald Trump in the Demilitarized Zone that straddles the Koreas on June 30, 2019. Brendan Smialowski/AFP via Getty Images hide caption
A man watches a television screen showing a news broadcast with a picture of North Korea's latest satellite-carrying rocket launch, at a railway station in Seoul on Nov. 22. Jung Yeon-Je/AFP via Getty Images hide caption
In this pool photo distributed by Sputnik agency, Russian President Vladimir Putin and North Korea's leader Kim Jong Un visit the Vostochny Cosmodrome in the Amur region on Wednesday. Mikhail Metzel/Pool/AFP via Getty Images hide caption
Travis King, a U.S. soldier, is believed to be in North Korean custody after he ran across the border on Tuesday. Reuters hide caption
In this photo taken on May 9, South Korean soldiers stand guard as they face North Korea in the Joint Security Area of the Demilitarized Zone separating North and South Korea. Anthony Wallace/AFP via Getty Images hide caption
In this photo provided by the North Korean government, North Korean leader Kim Jong Un, center, attends a meeting of the Central Committee of the ruling Workers' Party in Pyongyang, North Korea. AP File Photo hide caption
North Korean Kang Ho-Rye (second from left), 89, hugs her South Korean relative at a resort at Mount Kumgang, North Korea, in August 2018. Almost 100 South Koreans crossed the armed border to the North to meet their separated families. The U.S. bars citizens from entering North Korea, but some Korean Americans hope the Biden administration will lift the ban and let them visit again. Lee Su-Kil/Pool/Getty Images hide caption
A woman wearing a protective mask to help curb the spread of the coronavirus walks in front of he Olympic Rings on Tuesday in Tokyo. North Korea says it will not attend the games over COVID-19 fears. Eugene Hoshiko/AP hide caption
Experts worry that North Korea may be about to test an advanced solid-fuel missile. Wong Maye-E/AP hide caption
John Bolton after a meeting in Minsk, Belarus, in late August, nearly two weeks before his ouster as President Trump's national security adviser. Sergei Gapon/AFP via Getty Images hide caption
Protesters hold a banner showing images, of President Trump, Secretary of State Mike Pompeo, and National Security Adviser John Bolton during a rally against U.S. sanctions on North Korea, near the U.S. Embassy in Seoul, South Korea. Ahn Young-joon/AP hide caption
President Trump and North Korea's leader Kim Jong Un (right) hold a bilateral meeting during the second U.S.-North Korea summit in Hanoi, Vietnam, on Thursday. Saul Loeb/AFP/Getty Images hide caption
In this Dec. 12, 2012, file photo released by Korean Central News Agency, North Korea's Unha-3 rocket lifts off from the Sohae launch pad in Tongchang-ri, North Korea. In 2018, North Korea's government said it would destroy the facility. KCNA via AP hide caption