Russian president Vladimir Putin (L) and US president Donald Trump (R) pose for a photo during a bilateral meeting on the sidelines of the G20 summit in Osaka, Japan on Friday. Photograph: Michael Klimentyev/EPA

President Donald Trump issued a light-hearted warning to Russian President Vladimir Putin against meddling in US elections, laughing and smiling as he told his counterpart not to interfere when they met at the G-20 summit in Osaka. Video: Reuters

US president Donald Trump has reignited the controversy over claims that Russia helped put him in power by appearing to make a joke of it with the country’s leader, Vladimir Putin.

In a photo op before the two men met for discussions at the G20 summit in Osaka, Mr Trump smirked and wagged his finger at Mr Putin, saying “Don’t meddle in the election, please.”

US intelligence agencies concluded two years ago that Russia ran a campaign during the 2016 presidential election aimed at “undermining public faith in the US democratic process” and “harming the electability” of Mr Trump’s main rival, Hillary Clinton.

The Group of 20 leaders arrived in Osaka during a tropical cyclone, giving journalists an easy metaphor for what could be a stormy set of political meetings.

Mr Putin helped set the tone for the two-day summit when he praised Mr Trump’s US border campaign against migrants from Mexico and said his surprise election showed that western liberalism is “obsolete.”

Speaking to the Financial Times the Russian leader said the rise of populist right-wing movements in the US and Europe showed that liberalism and multiculturalism were “no longer tenable”.

“Traditional values are more stable and more important for millions of people than this liberal idea, which, in my opinion, is really ceasing to exist.”

The comments, aimed right at the heart of the EU project, drew a pointed response from European council president Donald Tusk, who told reporters at the summit he “strongly disagreed” with Mt Putin.

“Whoever claims that liberal democracy is obsolete, also claims that freedoms are obsolete, that the rule of law is obsolete and that human rights are obsolete,” he said.

“What I find really obsolete are authoritarianism, personality cults, the rule of oligarchs, even if sometimes they may seem effective.”

Skripal killing Later in Osaka, Mr Putin met a stony-faced Theresa May for a private meeting. The British prime minister said she would demand that he help bring two suspects in last year’s poisoning of former Russian spy Sergei Skripal in Salisbury to justice.

“There cannot be a normalisation of our bilateral relationship until Russia stops the irresponsible and destabilising activity,” Mrs May told Mr Putin, according to her handlers.

Mr Trump’s swaggering political style had already imposed itself on the summit before his arrival thanks to his threats of a trade war against China and India, the world’s second and sixth-largest economies.

In an interview with Fox television, the president also took aim at Japan, America’s closest Asian ally, which he appeared to suggest was enjoying a free defence ride at America’s expense.

“Almost all countries in this world take tremendous advantage of the United States . . . Like even Japan on the treaty, we have a treaty with Japan. If Japan is attacked, we will fight World War Three,” Mr Trump said.

“We will go in and we will protect them and we will fight with our lives and with our treasure. We will fight at all costs, right? But if we’re attacked, Japan doesn’t have to help us at all. They can watch it on a Sony television, the attack.”

Military bases Japan hosts about 50,000 US troops, and dozens of military bases – more than any other American ally. Japanese taxpayers have paid 6.6 trillion yen toward their cost over the last four decades.

China, meanwhile, pledged to resist attempts to “bully” it into making concessions after Mr Trump threatened earlier this month to slap an additional $325 billion worth of tariffs on imported Chinese goods – unless President Xi Jinping came to the table.