President Trump meets with North Korean leader Kim Jong Un in Singapore on Tuesday. (Evan Vucci/AP)

SEOUL — On Saturday in Canada, the image that captured the moment was a stone-faced President Trump sitting alone against some of the closest U.S. allies as the Group of Seven summit turned into a revolt against White House trade policies.

On Tuesday in Singapore, Trump mugged for the cameras with a grin and a thumbs up for the leader of a regime that remains under crippling U.N. sanctions for nuclear weapons tests and whose long list of rights abuses includes political prisons and accusations of state-directed torture.

Every word and gesture from Tuesday’s historic encounter between Trump and North Korean leader Kim Jong Un will be parsed and reparsed. But to students of high-stakes diplomacy, the photo of Trump's apparent bromance with Kim will probably seem more suited for a campaign stop or a meeting with America’s international partners — say, for example, the G-7 industrialized powers.

Not the type of chummy move you make with a dictator who has threatened that his missiles could reach U.S. shores and who has traded bellicose bluster with Trump.

Supporters of the American president will say this is just Trump being Trump. Others are likely to interpret the show of bonding with Kim as going too far, even under Trumpian rules.

When President Bill Clinton met Kim’s father, Kim Jong Il, in 2009, he was careful not to smile or offer any added fodder for those critical of the outreach to the then-North Korean leader.

Trump went just the other route. He said it was “my honor” to meet Kim.

“And we will have a terrific relationship, I have no doubt,” Trump said.

Kim, speaking in Korean, said that “the old prejudices and practices worked as obstacles on our way forward, but we’ve overcome all of them, and we are here today.”

It only took a few minutes for Trump to flip his thumbs up. Both Kim and Trump kept their expressions serious during their handshake — the first between a serving U.S. president and a North Korean leader.

The handshake took its place amid some of the most history-making political meetings of the past decades, joining such landmark encounters as the ones between President Barack Obama and Cuban leader Raúl Castro in 2013 and Israeli Prime Minister Yitzhak Rabin and Palestinian leader Yasser Arafat in Oslo in 1993.

Minutes later, during a session for photographers, Trump hijacked the solemnity of the handshake with a signature flick of the thumb.

The Twitter world took immediate notice.