US President Donald Trump meets other world leaders at Germany's G20 summit from Friday, with North Korea's first successful test of an intercontinental ballistic missile casting a long shadow over the gathering at the heavily-fortified venue.
The rising global threat posed by Pyongyang is likely to see conflicts over climate and trade take a back seat as regional neighbours China, Japan and South Korea gather with Trump and Russian strongman Vladimir Putin in Hamburg.
"Testing an ICBM represents a new escalation of the threat to the United States, our allies and partners, the region, and the world," US Secretary of State Rex Tillerson said, confirming North Korea now possessed a weapon capable of reaching US territory.
Russia and China condemned Tuesday's test and the European Union may consider additional sanctions.
All eyes will be on Trump, who had vowed North Korea's goal of possessing an ICBM "won't happen" and has repeatedly pressed China to rein in its truculent neighbour.
In the most anticipated moment of the G20, Trump will meet Putin, the ex-KGB agent accused of having aided, with hackers and fake news, the surprise rise of the property tycoon into the White House.
The moment they shake hands is sure to see "an Olympian level of macho posturing between these two leaders, who both understand the importance of symbolism and the perception of being tough," said Derek Chollet of the German Marshall Fund of the United States.
Trump ruffled other leaders at a G7 meeting in Italy in May and has steered the economic and military superpower on an isolationist "America First" course.
His counterparts are bracing for fresh surprises after Trump stunned the world by pulling out of the 2015 Paris climate pact, questioned long-standing NATO allegiances and dismissed free trade principles.