Talks between Donald Trump and Vladimir Putin, a much-anticipated box office event at an Asia-Pacific summit, were up in the air Saturday as the leaders swapped warm greetings in Vietnam but kept the world guessing on a formal meeting.
The question of whether the US and Russian leaders will hold official discussions on the sidelines of the APEC summit in the resort city of Danang has added a layer of diplomatic intrigue to an event dominated by trade discussions.
Trump's relationship with Moscow has haunted the first year of his presidency, with key former aides under a US investigation for alleged collaboration with the Kremlin.
Overly amicable talks between Trump and Putin would be an awkward sell for the White House as it denies any wrongdoing.
Instead a delicate diplomatic dance has been on show, giving glimpses of a warm relationship but no substantive talks.
The two men have met in Danang three times since late Friday, when they posed for a photo side by side in loose-fitting blue shirts custom made for the summit.
They again warmly shook hands on Saturday morning as leaders sat down for talks and then briefly chatted as they walked together to a podium for a "family photo" of attendees.
Moscow's top diplomat Sergei Lavrov also had a short meeting with his US counterpart Rex Tillerson.
Asked to give details on their talks, Lavrov glibly replied "I can, but I wouldn't".
Russia has denied allegations of interfering in the US election last year, won by Trump in a shock victory.
Trump's former campaign chairman Paul Manafort and an associate are under house arrest on charges including conspiracy to launder money, linked to the investigation by special counsel Robert Mueller into allegations that the campaign colluded with Russia.
Yet the US leader also wants Russian support for his efforts to isolate North Korea in a bid to restrain its nuclear ambitions.