Trump to face Middle East challenges in G20 summit

The growing tensions between the US and Iran, predicaments that he faces in trade with China and the threat of fresh election interference by Russia are just some of the issues he face.

His calendar in Osaka includes meetings with Russian President Vladimir Putin, Chinese President Xi Jinping, Turkey's Recep Teyyip Erdogan and Saudi Crown Prince Mohammed bin Salman.

Trump's meeting with Erdogan will be his first since announcing, and then backing off, a withdrawal of US forces from Syria. There also is a growing rift between the two NATO allies over Turkey's planned purchase of a Russian surface-to-air missile system and a US threat to suspend planned deliveries to Turkey of the F-35 Joint Strike Fighter.

The president left Washington days after pulling back from the brink of armed conflict with Iran and as he trades threats over its nuclear program and support for terror groups.

With Iran threatening to breach uranium enrichment limits set in the 2015 nuclear accord as soon as Thursday, Trump will be asked to articulate his strategy for containing Iran to sceptical world leaders after pulling the US from the deal last year.

Trump will also find himself face-to-face with Russian President Vladimir Putin for the first time since special counsel Robert Mueller's investigation ended without finding evidence that the Trump campaign criminally conspired with Russia during the 2016 election.

It will also be their first meeting since their summit in Helsinki in July 2018, when Trump declined to side with US intelligence agencies over Putin on the question of election interference, leading to an uproar at home and abroad.

Trump told reporters as he left the White House that he expects a "very good conversation" with Putin but added that "what I say to him is none of your business".