Separately meeting with President Vladimir Putin of Russia at the G-20 summit in Japan on Friday, President Trump and British Prime Minister Theresa May offered two very different examples of how to deal with the Russian leader.

Theresa May gave a far better one. Unlike Trump, she treated Putin as he presently deserves to be treated — as a powerful world leader deserving of dialogue but not affection. Walking up to Putin, May offered a curt handshake and then posed for the leader photograph with a particularly dour expression. It was the right thing to do, considering his involvement in an attempted assassination (and a resulting accidental killing) on British soil.

Russian President Vladimir Putin and British Prime Minister Theresa May meet on the sidelines of the G-20 summit in Osaka, western Japan, Friday, June 28, 2019. (AP)

Putin is responsible for a litany of ongoing affronts to western security. But the Russian leader is also directly culpable for the March 2018 high-toxicity nerve agent attack on a Russian defector and his daughter. That callous attack, conducted by the Russian GRU intelligence service with capricious disregard for civilian life, led to the painful July 2018 death of an innocent Briton, Dawn Sturgess.

And what has Putin done in the aftermath of this injustice? His government has made jokes at the expense of Sturgess' grieving children, and mocked the country it attacked. That alone deserves May's visible, public anger on Friday.

Contrast that with Trump's meeting with Putin. While Trump's Russia policy is rightly far tougher than President Barack Obama's ever was, he is always weirdly deferential to Putin in person. Such was the case this time. As Putin walked into their meeting room, Trump grasped his hand with a jolly smile. As Putin then efficiently greeted the U.S. delegation, Trump joked with Russian Foreign Minister Sergey Lavrov and affectionately patted Putin's spokesman, Dmitry "the watch" Peskov.

President Trump and Russian President Vladimir Putin greet each other at the G-20 summit in Osaka, Japan. (Mikhail Klimentyev/AP)

Trump then proceeded to explain his "great honor" to meet with Putin. Finally, Trump made light of a reporter's question as to whether he would demand Putin cease any attacks on the U.S. election.

It was a silly and sad display.

Discourse with Putin is important. But it must always recognize Putin's brutal realpolitik philosophy, and his disdain for America. Until Putin changes his approach to the West, Trump should stop treating Putin like a long lost friend.