Relations between South and North Korea have warmed rapidly since North Korean leader Kim Jong-un said in his New Year's Day address that the country was willing to participate in the PyeongChang Olympics.
Dr Petrov said the timing of the handshake was important with the United States and South Korea's annual joint military exercises, postponed due to the Winter Olympic Games and set to go ahead in February and March.
The delegation also included North Korea's supreme leader Kim Jong-un's younger sister Kim Yo-jong.
Pence and his wife, Karen, reportedly were the only people in that suite not to stand for the Korean delegation, which was made up of South Korean and North Korean athletes during the parade.
In 1951, 17-year-old Jack Keep enlisted in the U.S. Navy, and in early 1953 was assigned to Task Force 77 as a petty officer aboard a ship patrolling the North Korean coast. The overture follows heightened tensions over the North's missile tests.
The games are being held about 80 kilometres (50 miles) from the border between North and South Korea, countries that technically have been at war since 1950.
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North Korea's nominal head of state Kim Yong Nam also partook in the luncheon with Moon, CBS News' Jacqueline Alemany reports. They may also see a performance by a visiting North Korean art troupe in Seoul on Sunday before flying back to Pyongyang.
Against this backdrop, the United States managed to hold the alliance together in order to get what it wanted, thanks to its military and economic powers.
South and North Korea last marched together at the 2006 Winter Olympics in Turin.
Pence, who's leading the US delegation to the Olympics, made stops this week in Alaska, Japan and Seoul before arriving at the Olympic stadium in PyeongChang.
Moon has expressed his intention to use the Winter Olympics as a chance to make diplomatic inroads with the North and restore normalized communications, following months of high tensions on the Peninsula.
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The president made no mention of the women Mr. "He says it didn't happen", the president told reporters at the White House. In Porter's case, both of his ex-wives told a news publication that he had physically and verbally abused them.
"The Koreans will think it's a mood kill", said Frank Jannuzi, an expert on East Asia at the Mansfield Foundation in Washington.
The attack on the servers of the organisers of the Games led to malfunctions that disrupted the Main Press Center, the PyeongChang Organizing Committee for the 2018 Olympic & Paralympic Games (POCOG).
"It is absolutely necessary for the North and the United States to engage in talks at an early date", he cited Moon as saying.
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