In Osaka, it was the G-20 — a summit of leaders of the top 20 economic powers.

In Miami, it was the D-20 — debates featuring the top 20 Democratic candidates for president.

The agendas, and the rhetoric, revealed much about today's geopolitics.

In Japan, the focus wasn't conflict between nations, but transnational challenges or domestic dynamics vexing every country. "Main themes" noted by the host nation were the global economy, trade and investment, innovation, and development, as well as closely related issues like the environment and energy, health, women's empowerment and employment.

Not officially on the G-20 agenda, but on world leaders' minds, were the spiraling crises in North Korea, Iran and other countries contesting the global order by weapons proliferation or state-sponsored terrorism.

And the existential threat identified by many presidential candidates as the top international challenge, climate change, wasn't a separate summit agenda item and wasn't the subject of a separate debate among the Democrats, as some advocates and candidates called for.

Still, several presidential prospects, including Beto O'Rourke, Cory Booker, Julian Castro and Jay Inslee, named climate change when asked what they considered to be the biggest geopolitical threat to America.

Actually, Inslee first mentioned President Donald Trump, who was en route to the G-20 when night one of the D-20 occurred. While he initially used his travel status as a rare reason for radio (actually, Twitter) silence, Trump soon tweeted: "Sorry, I'm on Air Force One, off to save the FREE WORLD." But then the president prodded viewers to follow @TrumpWarRoom and other sites for "RAPID RESPONSE, FACT CHECKING and the TRUTH!" and later declared the debate "BORING!".

While the D-20 candidates (and probably most G-20 leaders) don't consider the president a likely savior of the free world, democracy itself is in peril worldwide, according to "The Third Wave of Autocratization," an influential article that was analyzed in a Carnegie Endowment of Peace piece on Thursday.

The pernicious trend is "more incremental and inconspicuous than in the past," the analysis stated, and this stealth theft of democracy and freedom may be just the way leaders like Russian President Vladimir Putin and Chinese President Xi Jinping like it.

In fact, it might help explain Xi's tactical retreat after millions in Hong Kong took to the street to fight a proposed extradition law that could have resulted in its citizens being subject to China's Kafkaesque justice system.

But Beijing is playing the long game, albeit with up-to-the-minute tools, a point identified by Pete Buttigieg, who said in Thursday's debate that, "if you look at what China is doing, they're using technology for the perfection of dictatorship." The South Bend, Ind., mayor later added that "their authoritarian model is being held up as an alternative to ours because ours looks so chaotic."

Republican and Democratic presidents alike used to tout the U.S. model and often allied America with democracy movements — sometimes in a unified front with leaders from NATO nations at events like G-20 summits. But Trump started the summit "lashing out at America's allies," while saying nothing negative about Xi and Putin, according to a report from the New York Times.

Asked what he and the Russian leader — whose government acted on behalf of Trump in the 2016 election, according to a Director of National Intelligence report — would talk about in their bilateral meeting, Trump told reporters earlier this week that, "What I say to him is none of your business."

It is America's business, however. Russia attacked the DNA of our democracy. When asked after his meeting if he sent a warning to the Kremlin leader, Trump, with a slight grin, turned to Putin and said, "Don't meddle in the election, president."

Some D-20 candidates did indeed identify Russia as America's main geopolitical threat. But over the two debate nights, most of the focus on how international issues hit home was about the border crisis. Many, including Julian Castro (who had a bit of a breakthrough because of his passionate advocacy on the issue), focused on the domestic dynamics. But some instead suggested that beleaguered Central America nations were more central to the issue.

At least the D-20 wrestled with the wrenching challenges and choices in the open: The global migration crisis wasn't a formal G-20 agenda item even though it's already roiled politics across continents, and may be a major contributing factor in the authoritarian wave debated by Carnegie scholars, among others.

A record 68.5 million people are forcibly displaced due to wars, violence and persecution, the U.N. reported on last week's World Refugee Day. Many others are economic migrants, and soon climate change — or the climate crisis, as Kamala Harris called it in the debate — may uproot millions more in an amplified destabilization dynamic that may further spur geopolitical challenges.

American leadership is essential in combating climate change and the democracy deficit it threatens to exacerbate. But the president didn't prioritize this at the G-20, and the D-20 sentiment seemed to be about disengaging, as evidenced by the reaction to Tulsi Gabbard's call to pull out of Afghanistan, which was even echoed by Joe Biden, who was vice president during a surge meant to stabilize that country.

But America needn't go it alone: International institutions like the G-20 itself, as well as alliances, are meant to address global problems in a multilateral manner.

So it was telling that Biden and Harris, despite disagreeing in the D-20 debates' most acrimonious moment, agreed that the first relationship they'd reset as president would be with NATO.

Soon the D-20 will be reduced to fewer candidates. But the global challenges just seem to increase. A more manageable debate that's just focused on foreign policy would better serve the nation and — considering America's outsized global role — the world.

John Rash is a Star Tribune editorial writer and columnist. The Rash Report can be heard at 8:20 a.m. Fridays on WCCO Radio, 830-AM. On Twitter: @rashreport.