Obama and Putin were to give competing speeches in short succession at the UN General Assembly in New York on Monday, with the two leaders also due to come face-to-face at a separate meeting for the first time in nearly a year.
The focus of Obama's speech is likely to be on the conflict in Syria, with Washington increasingly concerned at a Russian military build-up in the Middle East country, aimed at bolstering the power of Syrian President Bashar al-Assad, who Western powers say is responsible for most of the 240,000 deaths in the four-and-a-half-year-long war.
Obama is expected to call for a political resolution to Syria's civil war that includes Assad's ouster. This position contrasts strongly with that of Putin, who is likely to reiterate a call for collective international action against the jihadist group "Islamic State" in Syria Iran and Russia insist on role for Assad regime in Syriawith the involvement of Assad's forces.#
"There is no other solution to the Syrian crisis than strengthening the effective government structures and rendering them help in fighting terrorism," Putin told US television broadcaster CBS in an interview that aired on Sunday.
Putin's speech on Monday will mark the first time he has made a speech before the General Assembly in a decade.
At a later meeting between the two leaders on the sidelines of the UN event, Obama is likely to want to focus also on the situation in Ukraine, where Kyiv, Washington and NATO accuse Moscow of backing and supplying a pro-Russian insurgency in the east of the country. The US has led efforts in imposing sanctions on Russia over its actions in Ukraine, which include the annexation of Crimea last year.
The Kremlin, which has always denied the accusations, however, said that the topic of Ukraine would be discussed only if time allowed, with the fight against Islamic State in Syria taking the foreground.
Although the speeches by Obama and Putin are likely to draw the most attention, other world leaders among the some 160 expected to attend the meeting will also touch on globally sensitive topics.
Iran's president, Hassan Rouhani, will speak before the body for the first time since the signing of a key deal with world powers in July that will see international sanctions eased over Tehran's nuclear program. Ahead of his address, Rouhani said Iran would be willing to release three Americans from jail in a prisoner swap for its citizens held over sanctions violations.
President Francois Hollande of France will also be speaking, a day after French warplanes France carries out airstrikes against IS in Syrialaunched their first strikes against "IS" militants in Syria.
And China's Xi Jinping will make his UN debut speech amid tensions caused by cyber-spying affairs that Washington has blamed on Beijing.
Other firsts at the meeting include speeches by Cuban President Raul Castro and Nigerian leader Muhammadu Buhari, who was elected in March and has vowed to defeat Boko Haram Islamists who have carried out numerous atrocities in the region.
The General Assembly is a world body representing all 193 UN member states, and provides a platform for discussing global issues. However, its recommendations have no binding power.
Its annual meeting in September every year is called the General Debate, which this year has a special importance, falling as it does in the 70th year since the world body's foundation.
tj/kms (AP, AFP)