BERLIN • United States President Donald Trump meets other world leaders at Germany's two-day Group of 20 summit from tomorrow, with conflicts looming over climate, trade and other global issues both inside and outside the heavily fortified venue.
Fears over nuclear-armed North Korea, which just successfully tested an intercontinental ballistic missile (ICBM), cast another long shadow over the gathering, which will bring the leaders of China, Japan and South Korea to the northern city of Hamburg.
Prime Minister Lee Hsien Loong will also attend the summit. Although Singapore is not a member, it is participating as a representative of the Global Governance Group, a group of 30 small and medium-sized countries that aims to promote greater transparency and inclusivity in the G-20 process.
About 20,000 police officers will guard the heads of the G-20 big industrialised and emerging economies against anti-capitalist protesters, who are greeting them with the combative slogan "G-20 - Welcome to Hell".
But trouble is also brewing at the conference table at a time when the West and Europe are deeply divided and China and Russia are asserting themselves on the global stage.
All eyes will be on Mr Trump, who had vowed North Korea's goal of developing a nuclear weapon that can reach the US "won't happen" and has repeatedly pressed China to rein in its truculent neighbour.
His counterparts are bracing themselves for fresh surprises after Mr Trump stunned the world by pulling out of the 2015 Paris climate pact, questioned longstanding Nato allegiances and dismissed free-trade principles.
"There is a danger that the summit will lead to polarisation between the US and other countries" on climate change and other issues, warned economist Adam Slater from Oxford Economics.
Trade wars loom as Mr Trump has demanded Germany and China reduce their huge surpluses and his administration has threatened other countries with punitive measures in battles over cars, steel and natural gas.
In the most anticipated moment of the G-20, Mr Trump will meet Russian President Vladimir Putin, the former KGB agent accused of having aided, with hackers and fake news, the surprise ascent of the property tycoon to the White House.
The year's biggest diplomatic event outside the United Nations will also provide a stage for other world leaders muscling for power and regional influence.
Chinese President Xi Jinping, who met German Chancellor Angela Merkel in Berlin yesterday, will hold talks with regional rival Japan's Prime Minister Shinzo Abe, at a time when both increasingly worry about the threat posed by Pyongyang.
Also looming over the summit will be the bloody conflict in Syria and the frozen one in Ukraine - both involving Russia - as well as the struggle for dominance in the Middle East between Saudi Arabia and Iran.
The US President will today meet Dr Merkel.
Hailed by some as the "new leader of the free world", she advocates an internationalist approach to global issues - but her G-20 motto, "Shaping an Interconnected World", contrasts sharply with Mr Trump's go-it-alone approach.
In Hamburg, she must walk a fine line between trying to build a 19-1 front against Mr Trump on key issues and preventing further damage to transatlantic ties, while seeking common ground for at least a watered-down final G-20 communique.
On the streets, up to 100,000 protesters will march in about 30 rallies, creating a security headache in Germany's second-largest city.
In a sign of what may come, police overnight clashed with hundreds of protesters as they cleared out a protest camp, using pepper spray and water cannon against activists on the streets.
Police expect up to 8,000 leftwing radicals. The protesters are a diverse group of environmentalists, peace and anti-poverty activists, united in the belief that the world's elite is failing to solve pressing global problems.