President Donald Trump and President Vladimir Putin shared an oddly warm greeting during a ceremony marking the centennial of the armistice that ended World War I on Sunday.

The internet seems to think the pair greeted each other more like old friends than competing world leaders.

Trump, Putin and dozens of fellow world leaders gathered at the Arc de Triomphe in central Paris to commemorate the over 8 million people who died in World War I, which ended 100 years ago on Sunday. French President Emmanuel Macron led the ceremonies, warning of the continued danger of unchecked nationalism in a speech.

Trump smiled upon seeing Putin, a reaction that stood out among the relatively grim faces of other nearby world leaders Emmanuel Macron of France and Angela Merkel of Germany.

The smile prompted more than a few criticisms from online commentators.

Upon shaking hands, Putin flashed Trump a quick thumbs up in a moment caught on video.

Some took the opportunity to mock Trump’s continued chummy relationship with the Russian leader.

In the past, Trump has appeared to side with the Russian president over his own intelligence agencies and ignored warnings from his national security advisors not to congratulate Putin on his reelection. Putin has been accused of rigging the 2018 Russian elections.

The Kremlin said that Putin and Trump would meet in the midst of this weekend’s events, though Trump said earlier in the week that there was no time scheduled for a meeting.

Following Russia’s interference in the 2016 election and national security officials’ concerns about future attempts to disrupt U.S. electoral politics, the two nations maintain the tensest relations in decades.

Get our Politics Newsletter. The headlines out of Washington never seem to slow. Subscribe to The D.C. Brief to make sense of what matters most. Please enter a valid email address. Sign Up Now Check the box if you do not wish to receive promotional offers via email from TIME. You can unsubscribe at any time. By signing up you are agreeing to our Terms of Use and Privacy Policy . This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Thank you! For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.

Write to Alejandro de la Garza at alejandro.delagarza@time.com.