US president Barack Obama has arrived in Russia for a G20 summit overshadowed by a possible confrontation with Syria's key ally, Vladimir Putin, as well as foreign leaders sceptical of his call for an international military strike against Bashar Assad's government.
Mr Obama began a two-day visit to St Petersburg for the G20 economic summit, putting him in the same country as National Security Agency whistleblower Edward Snowden for the first time since the American fugitive fled to Moscow earlier this year.
Syria and Snowden have been sore points in an already-strained US-Russian relationship, fuelling the notion that Mr Obama and Russian president Vladimir Putin cannot get along.
Stepping out of his armoured limousine at the arrival ceremony, Mr Obama greeted his Russian counterpart with a few brief words and a handshake.
Turning to the waiting cameras, Mr Obama grinned before entering the ornate Constantine Palace. Praising the beauty of the palace, Mr Obama thanked his host, who smiled at the American leader. The starched, business-like exchange was the most highly anticipated of the summit, but lasted less than 20 seconds.
The White House went out of its way to say that while the two would cross paths at various meetings, Mr Obama would not be holding any one-on-one meetings with the Russian leader during his stay in St Petersburg.
Still struggling to drum up support at home for a strike on Syria, Mr Obama will seek to win over world leaders reluctant to get drawn into yet another US-led mission in the Middle East.
Although Syria is not formally on the agenda for the economy-focused summit, US officials are resigned to the fact that the bloody civil war there could overwhelm any talks about global economics.
Mr Putin's spokesman later said the US should wait for the report of UN inspectors who investigated a chemical attack in Syria before intervening militarily, adding that Washington's evidence of the Syrian regime's involvement is not strong enough.
Dmitry Peskov told a briefing on the sidelines of the G20 summit in Strelna outside St Petersburg that the US evidence "was quite far from being convincing" and urged Washington to wait for the findings of UN inspectors in Syria. He insisted that the UN Security Council is the sole body that can authorise the use of force.