SINGAPORE (AP) — Donald Trump approached from the right, striding down the long portico at the colonial-era Singapore resort. Kim Jong Un, dressed in his familiar Mao suit, emerged from the left. They met in the middle, on a red carpet, dozens of cameras recording their every move, as the world watched.

And counted.

Thirteen seconds. That's how long the American and North Korean leaders shook hands at the start of their summit Tuesday. The length of the contact, their facial expressions and body language, the stunning backdrop of interlocked national flags — all of it was instantly analyzed, criticized and marveled at in tweets and commentary in South Korea, the United States and beyond.

South Koreans applauded in a train station as they watched; the South Korean president grinned broadly; one official compared the summit, favorably, to the birth of his daughter. On the flipside, critics said the welcome Trump was giving Kim in Singapore would legitimize one of the world's worst human rights offenders.

It was a single, quintessentially human movement — a greeting, a welcome, a start of a relationship — but the reaction to the handshake was as complicated as the standoff that the two countries these men represent have been locked in for seven decades now.

There was shock, relief, worry, sometimes simultaneously, as the world watched Trump and Kim — who were insulting each other's mental and physical prowess and threatening nuclear war just a few months ago — shaking hands and smiling.

Trump put his hand out first, followed by Kim as they strode toward each other. Trump grasped Kim's right arm as they shook, and then, later, took ahold of Kim's left arm as they turned to face the cameras and the world, both their expressions momentarily deadening before they turned to face each other again, and smiled.

The backdrop was almost as shocking as the warmth of the handshake — a row of the two nations' flags displayed side-by-side at the entrance to the Singapore resort that's hosting their summit.

Both Koreas have long demonized the other's national flag. It's illegal to show the North Korean flag in the South, and even during the recent inter-Korean summit in the Demilitarized Zone there was no sign of the North's flag. North Korea's anti-U.S. iconography dates to the war and regularly shows North Korean soldiers bayonetting the U.S. flag.

However, many South Koreans rushed to express their awe of Tuesday's events.

The liberal Hankook Ilbo newspaper marveled that the U.S. president didn't shake hands in the usual "Trump way" of domineering his counterpart. It also noted that Trump softly tapped Kim on the shoulder and seemed to engage in small talk with him.

Jung Chung-rae, a former lawmaker of the liberal Minjoo Party, tweeted that the handshake "shined with courtesy and respect" and that history will remember their "handshakes and smiles." South Koreans watching television screens in a train station applauded the moment Trump and Kim met. Media photos showed South Korean President Moon Jae-in smiling broadly during a Cabinet meeting at the Blue House while watching a television screen that showed Trump and Kim shaking hands in front of American and North Korean flags. "All the attention of our people is on Singapore," Moon said. "I, too, could hardly sleep last night."

Shortly before the leaders met, Moon's chief of staff wrote on Facebook that the summit reminded him of his child's birth.

"I remember hovering around the delivery room the day my daughter was born. I didn't care whether you were a boy or a girl. Just come out to the world healthy with a big cry," Im Jong-seok wrote, apparently wishing for a successful outcome from the meeting between Trump and Kim.

Critics, however, saw the handshake and Kim's earlier moonlight stroll as evidence Trump was helping to legitimize Kim as his equal on the world stage even though the North Korean regime has been accused of horrific rights abuses. During his stroll Monday along the glittering Singapore waterfront, crowds yelled his name and jostled to take pictures, and the North Korean leader posed for a selfie with Singapore officials.

Last year Kim was "Little Rocket Man," according to Trump, and U.S. officials regularly mentioned his likely role in the assassination of his half-brother with nerve agent in a Malaysian airport, as well as his uncle's execution. Kim's image would now be bolstered, critics said.

Sue Mi Terry, a former CIA analyst, told MSNBC, "Kim Jong Un is prepared. He knows what he wants, which is to gain an ... international acceptance of North Korea as a nuclear weapons power. He thinks he's coming into this meeting from a position of strength because he has reached certain capability in his nuclear missile program. And he thinks he's going to now see what he can get out of the United States."

Adam Mount, a U.S. defense analyst, expressed anger about seeing the U.S. and North Korean flags side by side. ?

"We should be working diligently to transform North Korea and our relationship with it," he tweeted. "But until that day, it's abhorrent to see a flag that stands for so much suffering and cruelty standing with ours."

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AP writer Kim Tong-hyung contributed to this report from Seoul.

Foster Klug is AP bureau chief in South Korea and has covered the Koreas since 2005. Follow at www.twitter.com/apklug

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