"Is your communications security good?" President Lee jokes, and Trump offers a piece of paper, causing a laughter.

The Chinese delegation also smiled at the"talks of the century" between the US and China, but tensions remained high with Japan.

(Seoul = Yonhap News) Reporter Kwon Sook-hee = During Chinese President Xi Jinping's visit to Korea for the first time in 11 years, he, who is usually characterized by a blank expression, was caught smiling brightly at several moments, drawing attention.

The scene of Lee Jae-myung laughing while responding to President Lee Jae-myung's joke with a joke, and his expression of laughter while meeting with US President Donald Trump for the first time in six years, are becoming a hot topic.

The biggest laugh came during a friendly exchange with President Lee on the 1st, the closing day of the Asia-Pacific Economic Cooperation (APEC) forum in Gyeongju and the last day of President Xi's visit to Korea.

At the unveiling of gifts from the Chinese side during a friendly exchange between the leaders of the two countries following the conclusion of the Korea-China summit held at the National Gyeongju Museum on this day, two smartphones from Xiaomi, China's leading smartphone manufacturer, caught the eye.

A Chinese official said that it was a gift for the president and the first lady, and emphasized that"it is Xiaomi's latest smartphone produced last year, and the display inside the smartphone is a Korean LG product."

This explanation suggests an intention to highlight that China's technological advancements are being achieved through collaboration with South Korea. Xiaomi is currently leading the Chinese market, surpassing Apple's iPhone.

At this time, the president made a rather sharp joke.

The president asked,"Is your communications security good?" and when he heard the interpreted sentence, instead of being flustered, Chairman Xi slightly tilted his head back and laughed out loud, causing laughter to erupt in the room as well.

The city council member then pointed to Xiaomi's smartphones and responded,"We need to check if there are any 'backdoors'."

The president continued the cheerful atmosphere by clapping his hands.

The fact that a country's leader directly mentioned"backdoors," which refer to the ability of governments or hackers to steal data or remotely manipulate devices through hidden functions inside the device, was enough to attract public attention.

This joke comes amidst ongoing concerns raised in various countries about personal information leaks related to Chinese companies' products and services.

Backdoor was also a keyword that emerged this year when China pointed out security concerns about Nvidia's H20, the world's leading artificial intelligence (AI) chip.

The city mayor also smiled several times during other gatherings with the president.

On the first day of the APEC summit on the 31st of last month, President Lee and Chairman Xi were caught smiling at their first meeting at the summit hall.

It was reported that a friendly atmosphere was created at this time when the mayor of the city expressed his gratitude for the delicious Hwangnam bread he had received as a gift to commemorate his arrival the day before.

The city mayor was also seen smiling while sitting next to President Lee at a banquet held at the Lahan Select Hotel in Gyeongju on the 1st and watching a performance by G-Dragon and others.

With major pending issues between South Korea and China, such as the Korean Peninsula nuclear issue and China's ban on Korean Wave, attention is being paid to the extent to which President Xi's visit to South Korea, the first in 11 years, will restore South Korea-China relations.

What is attracting even more attention overseas is the photo of the summit between President Trump and Chairman Xi released by the White House.

In dozens of photos released by the White House on the 30th of last month (local time) without any explanation, President Trump takes out a piece of paper and holds it out to Chairman Xi, who then makes an amused expression and bursts into laughter.

Not only the Chinese delegation but also the Chinese leader smiled and showed an interested expression, raising curiosity about what kind of paper President Trump held out.

The face of Wang Yi, director of the Foreign Affairs Office of the Communist Party of China Central Committee (and also the Minister of Foreign Affairs), who was famous for his solemn demeanor and sat immediately to the left of the city mayor, was also smiling, and Wang Wentao, the Minister of Commerce of China, who was sitting at the very end, was also smiling brightly.

On social media such as X (formerly Twitter), various satirical photos and opinions speculating on the contents of Trump's paper were posted one after another.

Netizens responded with comments such as,"It might be a picture of the character 'Winnie the Pooh', which is often used to satirize city comments, or it might be a joke about current issues between the US and China, such as tariffs or the Taiwan issue."

It is not known what the actual contents of the paper were, but regardless, the fact that the US and China, who had been growling at each other since President Trump's inauguration in January of this year, were laughing loudly while engaging in the so-called"talks of the century" garnered attention.

In fact, during his two-night, three-day visit to Korea, the city mayor maintained his characteristically expressionless expression at most official occasions, including commemorative photo sessions.

When the leaders of China and Japan took a commemorative photo, even though Japanese Prime Minister Sanae Takaichi smiled brightly, he did not loosen his stern expression.

Earlier, Japan's NHK analyzed on the 31st of last month that in Chinese diplomacy, the facial expressions and gestures of the leader also send important messages to the other country, and also paid attention to the facial expressions that President Xi would show during the first 'meeting' between the two leaders.

The media reported that when former Prime Minister Shinzo Abe visited Beijing, China in 2014, Xi Jinping's expression remained fixed when they took a commemorative photo together, and he remained silent and looked straight ahead even when Abe spoke to him.

He explained that this likely reflected the cooling Sino-Japanese relations at the time.

Chairman Xi, who maintained a stern expression during his first summit with Prime Minister Takaichi on the 31st of last month, displayed a relatively hardline stance, mentioning the"Murayama Statement," which contains reflections and apologies for Japan's history of aggression.