OSAKA, Japan — President Donald Trump is under pressure to take a firm stand against election interference Friday when he holds his first meeting with Russia’s Vladimir Putin since the special counsel found extensive evidence of Russian meddling in the 2016 U.S. election. U.S. officials are on high alert for more interference next year.

Trump said in advance he expected a “very good conversation” with Putin but told reporters that “what I say to him is none of your business.” His aides have grown worried that Trump could use the meeting to once again attack Robert Mueller’s probe on the world stage, particularly since the special counsel now has a date to testify before Congress next month.

Senate Democratic leader Chuck Schumer pressed the president Thursday to directly challenge the Russian leader on election interference and send a signal “not merely to Putin but to all of our adversaries that interfering with our election is unacceptable, and that they will pay a price — a strong price — for trying.”

Putin is among five world leaders with whom Trump will hold with one-on-one meetings Friday on the sidelines of the Group of 20 summit in Osaka. The president went into the meetings complaining that the U.S. has been “ripped off” by other nations for years and after publicly airing grievances with Germany, India and even host nation Japan, whose leaders are all on his schedule for the day.

Trump has complained in recent days that the U.S. military alliance with Japan is one-sided, said Germany was taking advantage of the U.S. on support for NATO and tweeted that India’s tariffs on the U.S. “must be withdrawn!” Trump also meets Friday with Brazil’s President Jair Bolsonaro, whom the American leader has come to view as a populist leader in his own image.

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Japanese Chief Cabinet Secretary Yoshihide Suga on Thursday brushed off Trump’s complaints that the Japan-U.S. security pact unfairly puts the burden only on the U.S. side, calling Trump’s remarks “irrelevant” and saying the obligations are balanced.

While Trump is in Asia, the Democrats vying to replace him next year are holding their first primary debates. Trump pronounced the opening night Wednesday to be “boring” and was due to be in summit meetings during part two on Thursday night.

Trump’s meeting with Putin will be the leaders’ first extended conversation since the two met in Helsinki, Finland, nearly a year ago. That’s when Trump set off an uproar by declining to say he believed the U.S. intelligence services’ conclusions over Putin’s denials of election interference.

While Trump has long placed a premium on establishing close personal ties with Putin, his government has increased sanctions and other pressures on the Russian government.

The Mueller report did not establish a criminal conspiracy between Trump associates and the Kremlin to sway the outcome of the election. The finding lifted a cloud over the White House even as tensions have increased between Washington and Moscow. While Trump has long placed a premium on establishing close personal ties with Putin, his government has increased sanctions and other pressures on the Russian government.

At a summit last November in Argentina, Trump canceled what would have been the leaders’ first post-Helsinki meeting after Russia seized two Ukrainian vessels and their crew in the Sea of Azor. Those crew members remain detained, yet Trump — who did briefly greet Putin in Buenos Aires — has opted to forge ahead with the meeting, which will likely include discussions about hotspots in Iran, Syria and Venezuela, as well as nuclear weapons.

The leaders last year announced their withdrawal from a key arms control pact, the 1987 Intermediate-Range Nuclear Forces Treaty. It is set to terminate this summer, raising fears of a new arms race. Another major nuclear agreement, the New Start treaty, is set to expire in 2021 unless Moscow and Washington negotiate an extension. Along with arms control frictions, Russia’s annexation of Crimea and its support for a separatist insurgency in eastern Ukraine also weigh heavily on Russia-U.S. relations.

But the backdrop, as always, will be Russia’s 2016 election interference.

Putin has denied that Russia meddled in the American election to help Trump win, even though Mueller uncovered extensive evidence to the contrary. That included a Russian military intelligence operation to break into Democratic Party emails and efforts by a “troll farm” to spread divisive rhetoric and undermine the U.S. political system by using phony social media accounts.

At the news conference that followed the Helsinki summit, Trump responded to a reporter’s question by declining to denounce Russia’s election interference or side with his own intelligence agencies over Putin. The two men also spent more than two hours in a private meeting in Helsinki with only their interpreters present; some U.S. intelligence officials were never briefed on the discussions.