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HAMBURG, Germany — President Donald Trump's G-20 trip was dominated by news of his "very robust" first meeting with Russian President Vladimir Putin — but other critical issues hinged on his ability to maneuver through diplomatic channels.

After Trump received a rough reception last month during the NATO summit, foreign policy experts predicted a similar coolness in Hamburg, especially after his recent policy pronouncements on climate and trade put him out of step with the other allies gathered in Germany.

But this international trip played better than that previous stop in Brussels, according to Jamie Fly, a senior fellow with the German Marshall Fund. Trump seemed to have "navigated some of the differences that everyone knew would exist with the Europeans," Fly said.

Optics was but one of Trump's challenges, however. These five issues are the top takeaways of the G-20 summit:

1. Trump continued to pressure China for help with North Korea.

Tensions over North Korea were already high before the G-20, with urgency for a resolution over how to rein in the isolated nation renewed after an intercontinental ballistic missile test earlier in the week.

"Something has to be done about it," Trump reiterated at the start of a bilateral meeting with Chinese President Xi Jinping on Saturday, adding that he appreciates what's been done by China regarding North Korea.

That's a new tone from the one Trump took days earlier, chastising China for growing its trade relations with the regime of Kim Jong Un.

"So much for China working with us – but we had to give it a try!" Trump tweeted Wednesday.

Trade between China and North Korea grew almost 40% in the first quarter. So much for China working with us - but we had to give it a try! — Donald J. Trump (@realDonaldTrump) July 5, 2017

The Xi-Trump meeting lasted over an hour and a half, Treasury Secretary Steven Mnuchin told reporters on the plane returning to Washington. It would have lasted longer, he said, "if we didn't have to get pulled out to leave."

Leaving Hamburg for Washington, D.C. and the WH. Just left China’s President Xi where we had an excellent meeting on trade & North Korea. — Donald J. Trump (@realDonaldTrump) July 8, 2017

The White House strategy in North Korea has counted heavily on a helping hand from the Chinese, but Secretary of State Rex Tillerson described their actions Friday as "uneven."

The United States has kept the pressure on Beijing, sanctioning a Chinese bank last week and excluding China from a trilateral meeting with leaders from South Korea and Japan prior to the start of the G-20. That meeting yielded a joint statement from the three countries, pressing for the early adoption of a new U.N. Security Council resolution that would put additional sanctions on North Korea to show "that there are serious consequences for its destabilizing, provocative, and escalatory actions."

U.S. bombers practiced their attack capabilities at a training range in South Korea on Friday, NBC News learned — a clear show of force to the North Korean regime just days after the country tested the intercontinental ballistic missile.

Local media reported that the bombers flew close to the demilitarized zone that separates North and South Korea, but they did not cross demarcation lines.

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2. The U.S. got the cold shoulder on climate change.

Perhaps the most-watched policy emerging from the summit of world leaders centered on climate change and the effect of Trump's withdrawal from the Paris Climate Agreement. After one climate-change session, German Chancellor Angela Merkel told reporters Trump participated and "even made a contribution" to discussions.

But by the end of the two-day summit, America was officially standing alone.

The United States was singled out in a G-20 statement for its stance on climate issues, and the other countries took the uncharacteristic step of noting America's lone position in rebuffing the accord.

"We take note of the decision of the United States of America to withdraw from the Paris Agreement," the end-of-summit document read. "The United States of America announced it will immediately cease the implementation of its current nationally-determined contribution and affirms its strong commitment to an approach that lowers emissions while supporting economic growth and improving energy security needs."

The other G-20 leaders called the Paris Agreement "irreversible" and French President Emmanuel Macron announced an end-of-year summit in France to mark the accord's two-year signing anniversary.

But the White House balked at the idea that the statement was done to brush aside the United States.

National Economic Council Director Gary Cohn told reporters on Air Force One that "it was never a situation where there was isolated forces" as "everyone accepted" the U.S. decision to get out of the Paris Agreement early on.

3. World leaders steeled themselves for trade tariffs.

Another subject that set the U.S. apart from its G-20 partners was trade, with leaders giving an early rebuttal to possible U.S.-imposed tariffs on steel imports, which may emerge from the White House soon.

On Friday, European leaders were direct in their opposition. European Commission President Jean-Claude Juncker promised, metaphorically, that "we are prepared to take up arms if need be," but hoped it wouldn't be "actually necessary."

President Donald Trump and German Chancellor Angela Merkel attend a panel discussion on the second day of the G20 summit on July 8, 2017, in Hamburg, Germany. Pool / Getty Images

Experts said before the G-20 that Germany was bracing for the possibility of tariffs, with Merkel speaking out prior to Trump's arrival about the "big mistake" of believing "isolationism and protectionism" could fix the world's problems.

In closing out the summit in her home country, Merkel told reporters that G-20 leaders were clear that markets must be open, while fighting against protectionism and unfair practices.

Fly, who served on the National Security Council and in the Pentagon when President George W. Bush was in office, said the Trump administration should be cautious on the pending tariffs decision.

He said that it needs to "make sure that they're not, at the end of the day, going after countries that are really not the root of the problem on that issue."

Trade tensions, he noted, are "added to all the other emotions about Trump and about Paris Climate Agreement withdrawal that the imposition of tariffs that affect our European allies would have a very negative impact on Trans-Atlantic relations."

4. A new 'de-escalation' deal for Syria comes into effect.

Tillerson announced Friday that the United States, in tandem with Russia and Jordan, agreed to a de-escalation in southwest Syria, a "first indication of the U.S. and Russia being able to work together in Syria."

The ceasefire went into effect at midday local time (5 a.m. ET) Sunday.

But there have been ceasefire attempts before amid the country's civil war, and questions remain over who will be monitoring the ISIS-ravaged region.

Related: Syria ‘De-Escalation’ Deal: What Is It, and Will it Work?

"At the end of the day, this is Syria," one senior State Department official said Friday, briefing reporters anonymously to better discuss details of the ceasefire deal and acknowledging the complications there.

There remains the question of what to do with Syrian President Bashar al-Assad. Tillerson has said of the country's future: "There will be a transition away from the Assad family."

5. Big dollars were committed to a women empowerment fund.

The White House pledged $50 million to a new World Bank initiative geared toward breaking down barriers to female economic empowerment.

The introduction of the Ivanka Trump-backed group drew Merkel, Trump and Canadian Prime Minister Justin Trudeau to the podium to praise efforts to help women entrepreneurs around the world achieve greater success with the help of loans, mentorships and policy reform.

Trump himself applauded the initiative for the "millions and millions" of women it would help to bolster, with Cohn touting it as an example of the administration's pro-woman mindset.

Ivanka Trump's White House role is nebulous, but she has consistently focused on projects that support female economic advancement. Her role in this particular initiative would not be one of a fundraiser, a senior administration official insisted, but instead, one of a global champion and advocate.